Note:

The notation "[X,Y]" denotes a closedinterval fromX toY, includingX andY;"[X,Y)" denotes a right half-openinterval fromX toY, includingX but not includingY;"(X,Y]" denotes a left half-openinterval fromX toY, not includingX but includingY;"(X,Y)" denotes an openinterval fromX toY, not includingX orY.

Note:

In this example, thep element is used as a presentationalelement rather than as a semantic element, i.e., as a linguistic paragraph.It is up to an author to determine which TTML elements are used to conveythe intended meaning. For instance, this example could be written to usetiming onspan elements in order to preserve the integrity ofsemantic paragraphs.

Note:

For example, the phrases "treat X as an error" and "consider Xas an error" are to be read as mandatory requirements in the context of use. Similarly, if the specificationprose is "X must apply", "X applies", or "X is mandatory", and "X" is further defined as "X is Y and Z",then, by transitive closure, this last declarative phrase is to be read as "Y is mandatory" and"Z is mandatory" in the context of use.

3.2.1 Generic Processor Conformance

A TTMLContent Processor conforms to this specification if the followinggeneric processor criteria aresatisfied:

1. The processor provides at least one mechanism for notionallyinstantiating a Reduced XMLInfoset representation of a conformantDocument Instance.

2. If a process does or can perform validation of a candidateDocument Instance, then it provides at least one mechanism toimplicitly or explicitly associate theReduced XML Infoset representationof a conformantDocument Instance with one of theAbstract Document Types defined by4 Document Types.

3. The processor does nota priori reject or abort theprocessing of a conformantDocument Instanceunless the processor does not support some required(mandatory) feature specified or implied by a TTML profiledeclared to apply to theDocument Instance.

4. The processor supports all mandatory processing semantics defined by this specification.

   Note:

   The phrasemandatory semantics refers to all explicit use of the conformancekey phrasesmust andmust not as well as anydeclarative statement that can be reasonably inferred from such key phrases. For example, thesemandatory semantics include support for all features marked as mandatory inD.2 Feature Support.

5. If the processor supports some optional processing semantics defined by this specification,then it does so in a manner consistent with the defined semantics.

   Note:

   The phraseoptional semantics refers to all explicit use of the conformancekey phrasesshould,should not,may, andmay not,as well as any declarative statement that can be reasonably inferred from such key phrases. For example, theseoptional semantics include support for all features marked as optional inD.2 Feature Support.

3.2.2 Transformation Processor Conformance

A TTMLContent Processor is a conformant TTMLTransformation Processor ifthe following criteria are satisfied:

1. The processor satisfies all requirements specified by3.2.1 Generic Processor Conformance.

2. The processor supports the DFXP Transformation profile as specifiedbyF.1 DFXP Transformation Profile.

3.2.3 Presentation Processor Conformance

A TTMLContent Processor is a conformant TTMLPresentation Processor ifthe following criteria are satisfied:

1. The processor satisfies all requirements specified by3.2.1 Generic Processor Conformance.

2. The processor supports the DFXP Presentation profile as specifiedbyF.2 DFXP Presentation Profile.

Note:

The schemas referenced by this specification do not validate all syntactic constraintsdefined by this specification, and, as such, represent a superset of conformantTTML Content. In particular, performing validation with one of the abovereferenced schemas may result in afalse positive indication of validity.For example, both the RNC and XSD schemas specifythat atts:fontFamily attribute mustsatisfy thexs:string XSD data type; however, this data type is a supersetof the values permitted to be used with thetts:fontFamily attribute.

In addition, the RNC schema may produce afalse negativeindication of validity when using thexml:id attribute with an element ina foreign namespace, thus representing a subset of conformant TTML Content. This isdue to a specific limitation in expressing wildcard patterns involvingxsd:IDtyped attributes in Relax NG schemas. Note that this specification defines theformal validity of aDocument Instance to be based on anAbstract Document Instance fromwhich all foreign namespace elements and attributes have been removed. Therefore, theexceptional reporting of this false negative does not impact the formal assessmentofDocument Instance validity.

Note:

The schemas referenced by this specification are intended for use after the pruning steps (1)-(3) specified by4 Document Types have been applied.

Note:

In a specificDocument Instance, it is not required that the defaultprefixes shown below are used. Any prefix or namespace binding that satisfies the constraintsof XML Namespaces[XML Namespaces 1.0] may be used that is associated with the specified namespace URI.

Note:

If a reference to an element type is used in this specification and the nameof the element type is not namespace qualified, then the TT Namespace applies.

For certain namespaces defined above, the default prefixis specified asnone if no XML vocabulary is defined inthe namespace by this specification (nor expected to be defined in afuture version of this specification). In such cases, the use of thenamespace URI is for purposes other than defining XML vocabulary,e.g., for designating profiles, features, extensions and fordereferencing standard profile definitions.

Note:

For example, if a profile designator is expressed asdfxp-presentation, then the absolutized profile designatorwould behttp://www.w3.org/ns/ttml/profile/dfxp-presentation.

Note:

It is not a requirement on a conformantDocument Instance that a profile be internallydefined by use of attp:profile element or internally referenced by attp:profile attribute. More specifically, it is permitted that theDocumentInterchange Context determines the applicable profile through privateagreement, out-of-band protocol, or common use (between sender and receiver) of a profile definedby an external specification.

Note:

It is intended that thettp:profile attribute be used whenthe author wishes to reference one of the standard, predefined profiles ofTTML Content, and does not wish to modify (by supersetting or subsetting)that profile. This attribute may also be used by an author to indicate the useof a non-standard profile, in which case the specified profile designator expressesa URI that denotes an externally definedProfile Definition Document.However, it is not required that a conformant TTML Content Processor be ableto dereference such an externally specified profile definition.

In contrast, it is intended that thettp:profile element beused when the author wishes to make use of a modified predefined profile orwishes to include in theDocument Instance a non-standard profile definitionnot based upon one of the predefined profiles.

A predefined profile is supersetted by specifying some feature or extension toberequired (mandatory) that was either not specified in the underlying, baselineprofile or was specified asoptional (voluntary) in the baseline profile.A predefined profile is subsetted by specifying some feature or extension tobeoptional (voluntary) that was specified asrequired (mandatory)in the underlying, baseline profile.

When a baseline profile is modified by subsetting, the resulting, derived profileis referred to as asubtractive profile; when modified by supersetting, the resultis referred to as anadditive profile.It is also possible to define a derived profile that is simultaneously subtractiveand additive.

Note:

Arequired feature orused featurespecification is expressed directly (or indirectly by referring to aprofile) by means of attp:featureelement where the value of itsvalue attribute isrequired oruse,respectively. Arequired extension orusedextension specification is expressed directly (or indirectly byreferring to a profile) by means of attp:extensionelement where the value of itsvalue attribute isrequired oruse,respectively.

Note:

In the above example, the baseline profile is declared to bethe DFXP Presentation profile, which is then additively modified by making the#fontStyle-italic feature required (rather thanoptional as it is definedinF.2 DFXP Presentation Profile). Note also the resetting of thedefault XMLNS binding on theprofile element to the TT Parameter Namespace.

5.3.1 Core Catalog

The core vocabulary catalog is intended to satisfy the needs ofTTML while providing a baseline vocabulary for future profiles. This vocabularyis divided into distinct categories, specified in detailin the following sections:

• 6 Parameters

• 7 Content

• 8 Styling

• 9 Layout

• 10 Timing

• 11 Animation

• 12 Metadata

The core element vocabulary specified for use with aDocument Instance is enumerated inTable 3 – Element Vocabulary.

Element vocabulary groups that are used in defining content modelsfor TTML element types are enumerated inTable 4 – Element Vocabulary Groups.

The attribute vocabulary specified for use with the core vocabularycatalog is enumerated inTable 5 – Attribute Vocabulary.

5.3.2 Extension Catalog

The extension vocabulary catalog is intended for use by futureprofiles of TTML, and is not further definedby this version of this specification.

In addition to standardized extension vocabulary, a conformingDocument Instance may contain arbitrary namespace qualifiedelements that reside in any namespace other than those namespacesdefined for use with this specification. Furthermore, a conformingDocument Instance may contain arbitrary namespace qualifiedattributes on TTML defined vocabulary where such attributes reside inany namespace other than those defined for use with thisspecification.

6.1.1 ttp:profile

Thettp:profile element is used to specify a collection ofused (mandatory and enabled), required (mandatory),and optional (voluntary) features and extensions that must ormay be supported by aContent Processor in order to process aDocument Instance that makes (or may make) use of such features andextensions.

This specification defines two distinct uses of thettp:profile element:

• as a child of thehead element within a TTMLDocument Instance;

• as the root element of a TTMLProfile Definition Documentinstance;

When attp:profile element appears within a TTMLDocument Instance,its purpose is to express authorial intentions about whichfeatures and extensions must or may be supported by a recipientcontent processor. In addition, the element indirectly expressesinformation about the set of features or extensions that are (or mayexpected to be) used by theDocument Instance.

When attp:profile element is used by a TTMLProfile Definition Document instance,it serves to publish a machinereadable specification of a specific TTML profile, of whichthis specification defines three suchProfile Definition Documents inF Profiles.

Thettp:profile element accepts as its children zero or moreelements in theMetadata.class element group, followed byzero or morettp:features elements, followed byzero or morettp:extensions elements.

<ttp:profile  use = stringxml:id = ID  {any attribute not in default or any TT namespace}>Content:Metadata.class*,ttp:features*,ttp:extensions*</ttp:profile>

If specified, theuse attribute must adhere to thexsd:anyURI data type defined by[XML Schema Part 2],§3.2.17, and, furthermore, must denote a profile designator inaccordance with5.2 Profiles. In this case,the profile designator must refer to (1) a standard, predefinedProfile Definition Document as defined byF Profiles,or (2) a feasibly dereferenceable resource representing a validProfile DefinitionDocument instance. In either case, the referenced profile serves as thebaseline profile of the specifyingttp:profile element.

If theuse attribute is not specified, then the baselineprofile of thettp:profile element must be considered to bethe empty (null) profile, i.e., a profile definition containing nofeature or extension specifications.

The collection of features and extensions of a profile are determined accordingto the following ordered rules:

1. initialize the features and extensions of the profile to the emptyset;

2. if ause attribute is present, then augment the profilewith the set of features and extensions specified by the referencedbaseline profile;

3. for eachttp:feature andttp:extension elementdescendant of thettp:profile element, using a post-ordertraversal, merge the specified feature or extension with the featuresand extensions of the profile, where merging a feature or extensionentails replacing an existing feature or extension specification, ifit already exists, or adding a new feature or extension specification,if it does not yet exist in the profile;

A conformant TTML processor is not required to be able todereference aProfile Definition Document that is not one of thestandard, predefined profiles defined byF Profiles. Furthermore,a conformant TTML processor may make use of a built-in, staticform of each standard, predefined profile so as not to requiredereferencing a network resource.

If a TTML processor is unable to dereference a non-standardProfile Definition Document, then it must not further process thedocument without the presence of an explicit override from an end-useror some implementation specific parameter traceable to an end-user orto a user or system configuration setting. If a TTML processor abortsprocessing of aDocument Instance due to the inability toreference a non-standardProfile Definition Document, then someend-user notification should be given unless the end-user or systemhas disabled such a notification, or if the processor does not permitor entail the intervention of an end-user.

Thettp:profile element is illustrated by the following example.

<ttp:profile use="dfxp-presentation">  <ttp:features xml:base="http://www.w3.org/ns/ttml/feature/">    <ttp:feature>#text-outline</ttp:feature>  </ttp:features></ttp:profile>

6.1.2 ttp:features

Thettp:features element is a container element used to groupinfomation about feature support requirements.

Thettp:features element accepts as its children zero or moreelements in theMetadata.class element group, followed byzero or morettp:feature elements.

<ttp:features  xml:base = string :TT Feature Namespacexml:id = ID  {any attribute not in default or any TT namespace}>Content:Metadata.class*,ttp:feature*</ttp:features>

If specified, thexml:baseattribute must (1) adhere to thexsd:anyURI data type defined by[XML Schema Part 2],§3.2.17, (2) express an absolute URI thatadheres to[XML Base] and,(3) express a feature namespace as defined byD.1 Feature Designations. If not specified, thexml:base attribute's defaultvalue applies, which is the TT Feature Namespace.

Thexml:base attribute isused to permit the abbreviation of feature designation URIs expressedby childttp:feature elements.

6.1.3 ttp:feature

Thettp:feature element is used to specifyinfomation about support requirements for a particular feature.

The children of thettp:feature element must express a non-emptysequence of character information items that adheres to thexsd:anyURI data type defined by[XML Schema Part 2],§3.2.17.

<ttp:feature  value = (optional|required|use) : requiredxml:id = ID  {any attribute not in default or any TT namespace}>Content: #PCDATA</ttp:feature>

If the URI expressed by the content of thettp:featureelement is a relative URI, then, when combined with thefeature namespace value expressed by thexml:base attribute of thenearest ancestorttp:features element, it must express anabsolute URI. In either case (original absolute URI or resultingabsolutized URI), the URI expressed by thettp:featureelement must further adhere to the syntax of a feature designation asdefined byD.1 Feature Designations, and, furthermore,the specific designation that appears in this URI, i.e., the portion of the feature designationthat starts with the fragment identifier separator '#', mustbe defined by this specification or some published version thereof (thathas achieved REC status).

If the URI expressed by the content of thettp:feature elementis a relative URI, then anxml:base attribute should bespecified on the nearest ancestorttp:features element.

Thevalue attribute specifies whether a conforming TTMLprocessor must or may implement the designated feature in order toprocess the document. If the value of thevalue attributeisoptional, then the processor neednot implement or otherwise support the feature in order to process thedocument; if the value isrequired, then the processormust implement or otherwise support the feature, irrespective ofwhether the feature is enabled or disabled, in order to processthe document; if the value isuse, then the processor must both (1) implement orotherwise support the feature and (2) have enabled (activated) use of thefeature.

If the value of thevalue attribute isrequired oruseand the TTML processor implementation doesnot support the feature, or if thevalue attribute isuse and the TTML processor implementation supports but has disabledthat feature, then it must not further process the documentwithout the presence of an explicit override from an end-user or someimplementation specific parameter traceable to an end-user or to auser or system configuration setting. If a TTML processor abortsprocessing of aDocument Instance due to the specification of arequired, but unsupported feature by this element, then some end-usernotification should be given unless the end-user or system hasdisabled such a notification, or if the processor does not permit orentail the intervention of an end-user.

If the value of thevalue attribute isoptional, and if the TTML processor implementation doesnot support the feature, then it may further process the document evenin the case that some use of the feature is present in the document.In the case of actual use of a feature designated as optional, thedefault semantics associated with that feature apply; that is, theprocessor may behave as if the feature were not actually used orreferenced by the document. Notwithstanding the above, the syntacticpresence or reference to an optional feature by a document must not beconsidered to be a violation of document validity or a barrier tofurther processing if the syntactic expression is well-formed andvalid.

If some defined (i.e., standardized) or otherwise well known feature is not specified byattp:feature element in a given profile, then it must be interpreted as if the feature were specifiedwith thevalue attribute equal tooptional.

Thettp:feature element is illustrated by the following example.

<ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-presentation">  <ttp:features xml:base="http://www.w3.org/ns/ttml/feature/"><ttp:feature value="required">#fontStyle-italic</ttp:feature><ttp:feature value="required">#textDecoration-under</ttp:feature>  </ttp:features></ttp:profile>

6.1.4 ttp:extensions

Thettp:extensions element is a container element used to groupinfomation about extension support requirements.

Thettp:extensions element accepts as its children zero or moreelements in theMetadata.class element group, followed byzero or morettp:extension elements.

<ttp:extensions  xml:base = string :TT Extension Namespacexml:id = ID  {any attribute not in default or any TT namespace}>Content:Metadata.class*,ttp:extension*</ttp:extensions>

If specified, thexml:baseattribute must (1) adhere to thexsd:anyURI data type defined by[XML Schema Part 2],§3.2.17, (2) express an absolute URI thatadheres to[XML Base] and,(3) express an extension namespace as defined byE.1 Extension Designations. If not specified, thexml:base attribute's defaultvalue applies, which is the TT Extension Namespace.

Thexml:base attribute isused to permit the abbreviation of feature designation URIs expressedby childttp:extension elements.

6.1.5 ttp:extension

Thettp:extension element is used to specifyinfomation about support requirements for a particular extension.

The children of thettp:extension element must express a non-emptysequence of character information items that adheres to thexsd:anyURI data type defined by[XML Schema Part 2],§3.2.17.

<ttp:extension  value = (optional|required|use) : requiredxml:id = ID  {any attribute not in default or any TT namespace}>Content: #PCDATA</ttp:extension>

If the URI expressed by the content of thettp:extensionelement is a relative URI, then, when combined with theextension namespace value expressed by thexml:base attribute of thenearest ancestorttp:extensions element, it must express anabsolute URI. In either case (original absolute URI or resultingabsolutized URI), the URI expressed by thettp:extensionelement must further adhere to the syntax of an extension designationas defined byE.1 Extension Designations.

If the URI expressed by the content of thettp:extension element is a relative URI, then anxml:base attribute should be specified on the nearestancestorttp:extensions element.

Thevalue attribute specifies whether a conforming TTMLprocessor must or may implement the designated extension in order toprocess the document. If the value of thevalue attributeisoptional, then the processor neednot implement or otherwise support the extension in order to process thedocument; if the value isrequired, then the processormust implement or otherwise support the extension in order to processthe document; if the value isuse, then the processor must both (1) implement orotherwise support the extension and (2) enable (activate) use of theextension.

If the value of thevalue attribute isrequired oruseand the TTML processor implementation doesnot support the extension, or if thevalue attribute isuse and the TTML processor implementation supports but has disabledthat extension, then it must not further process the document without thepresence of an explicit override from an end-user or someimplementation specific parameter traceable to an end-user or to auser or system configuration setting. If a TTML processor abortsprocessing of aDocument Instance due to the specification of arequired, but unsupported extension by this element, then someend-user notification should be given unless the end-user or systemhas disabled such a notification, or if the processor does not permitor entail the intervention of an end-user.

If the value of thevalue attribute isoptional, and if the TTML processor implementation doesnot support the extension, then it may further process the document evenin the case that some use of the extension is present in the document.In the case of actual use of an extension designated as optional, thedefault semantics associated with that extension apply; that is, theprocessor may behave as if the extension were not actually used orreferenced by the document. Notwithstanding the above, the syntacticpresence or reference to an optional extension by a document must not beconsidered to be a violation of document validity or a barrier tofurther processing if the syntactic expression is well-formed andvalid.

If some well known extension is not specified byattp:extension element in a given profile, then it must be interpreted as if the extension were specifiedwith thevalue attribute equal tooptional.

Thettp:extension element is illustrated by the following example.

<ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-transformation">  <ttp:extensions xml:base="http://example.org/ttml/extension/"><ttp:extension value="use">#prefilter-by-language</ttp:extension>  </ttp:extensions></ttp:profile>

6.2.1 ttp:cellResolution

Thettp:cellResolution attribute may be used by an authorto express the number of horizontal and vertical cells into which theRoot Container Regionarea is divided for the purpose of expressing presentation semantics in terms ofa uniform grid.

If specified, the value of this attribute must adhere to the following syntax:

ttp:cellResolution  : columns rows                            //columns != 0;rows != 0columns | rows  :<digit>+

If not specified, the number of columns and rows must be consideredto be 32 and 15, respectively. If specified, then columns or rows must not be zero (0).

Attp:cellResolution attribute is considered to be significant onlywhen specified on thett element.

Except where indicated otherwise, when a<length> expressed incells denotes a dimension parallel to the inline or block progression dimension,the cell's dimension in the inline or block progression dimension applies, respectively.

6.2.2 ttp:clockMode

Thettp:clockMode attribute is used to specify theinterpretation of time expressions as real-time time coordinates whenoperating with time base ofclock as defined by6.2.11 ttp:timeBase.

If specified, the value of this attribute must adhere to the following syntax:

ttp:clockMode  : "local"  | "gps"  | "utc"

If the time base, defined by6.2.11 ttp:timeBase, is designated asclock, then this parameter applies as follows: if theparameter's value islocal, then time expressions areinterpreted as local wall-clock time coordinates;ifutc, then time expressions areinterpreted as UTC time coordinates[UTC];ifgps, then time expressions areinterpreted as GPS time coordinates[GPS].

If not specified, the value of this parameter must be consideredto beutc.

Attp:clockMode attribute is considered to be significant onlywhen specified on thett element.

6.2.3 ttp:dropMode

Thettp:dropMode attribute is used to specifyconstraints on the interpretation and use of frame countsthat correspond with[SMPTE 12M] time coordinates when operatingwith time base ofsmpte as defined by6.2.11 ttp:timeBase.

If specified, the value of this attribute must adhere to the following syntax:

ttp:dropMode  : "dropNTSC"  | "dropPAL"  | "nonDrop"

If the time base, defined by6.2.11 ttp:timeBase, is designated assmpte, then this parameter applies as follows: if theparameter's value isnonDrop, then, within any givensecond of a time expression, frames count from 0 toN−1, whereN is the value specified bythettp:frameRate parameter, but while ignoring any valuespecified by thettp:frameRateMultiplier parameter.

If this parameter's value isdropNTSC, then, within anygiven second of a time expression except the second00,frames count from 0 toN−1, whereN isthe value specified by thettp:frameRate parameter, butwhile ignoring any value specified by thettp:frameRateMultiplier parameter. If the second of a timeexpression is00 and the minute of the time expression isnot00,10,20,30,40, or50, then frame codes00and01 are dropped during that second; otherwise, theseframe codes are not dropped.

If this parameter's value isdropPAL, then, within anygiven second of a time expression except the second00,frames count from 0 toN−1, whereN isthe value specified by thettp:frameRate parameter, butwhile ignoring any value specified by thettp:frameRateMultiplier parameter. If the second of a timeexpression is00 and the minute of the time expression iseven but not00,20, or40,then frame codes00 through03 are droppedduring that second; otherwise, these frame codes are not dropped.

If not specified, thennonDrop must be assumed to apply.

Attp:dropMode attribute is considered to be significant onlywhen specified on thett element.

6.2.4 ttp:frameRate

Thettp:frameRate attribute is used to specify the frame rate of a relatedmedia object or the intrinsic frame rate of aDocument Instance in case it is intendedto function as an independent media object.

If specified, the value of this attribute must adhere to the following syntax:

ttp:frameRate  :<digit>+                                //value > 0

The frame rate that applies to aDocument Instance is used tointerpret time expressions that are expressed inframesas defined by10.3.1 <timeExpression>.

If themedia time base applies and the effective frame rate isintegral, then a frame is interpreted as a division of a second of mediatime, such that if the frame rate is specified asF, thena second of media time is divided intoF intervals ofequal duration, where each interval is labeled as framef,withf ∈ [0…F−1].

If not specified, the frame rate must be considered to be equal to someapplication defined frame rate, or if no application defined frame rate applies,then thirty (30) frames per second. If specified, then the frame rate mustbe greater than zero (0).

Attp:frameRate attribute is considered to be significant onlywhen specified on thett element.

6.2.5 ttp:frameRateMultiplier

Thettp:frameRateMultiplier attribute is used tospecify a multiplier to be applied to the frame rate specified by attp:frameRate attribute in order to compute the effectiveframe rate.

If specified, the value of this attribute must adhere to the following syntax:

ttp:frameRateMultiplier  : numerator denominator                   //numerator != 0;denominator != 0numerator | denominator  :<digit>+

A frame rate multiplier is used when the desired frame rate cannotbe expressed as an integral number of frames per second.

If not specified, the frame rate multiplier must be considered to be equal to someapplication defined frame rate multiplier, or if no application defined frame rate multiplier applies, then one (1:1). Both numerator and denominator must be non-zero.

Attp:frameRateMultiplier attribute is considered to be significant onlywhen specified on thett element.

6.2.6 ttp:markerMode

Thettp:markerMode attribute is used to specifyconstraints on the interpretation and use of time expressionsthat correspond with[SMPTE 12M] time coordinates when operatingwith time base ofsmpte as defined by6.2.11 ttp:timeBase.

If specified, the value of this attribute must adhere to the following syntax:

ttp:markerMode  : "continuous"  | "discontinuous"

If the time base, defined by6.2.11 ttp:timeBase, is designated assmpte, then this parameter applies as follows: if theparameter's value iscontinuous, then[SMPTE 12M] time coordinatesmay be assumed to be linear and either monotonically increasing ordecreasing; however, ifdiscontinuous, then any assumptionmust not be made regarding linearity or monotonicity of time coordinates.

If not specified, the value of this parameter must be consideredto bediscontinuous.

Attp:markerMode attribute is considered to be significant onlywhen specified on thett element.

If a value ofcontinuous applies, then timeexpressions may be converted to real timecoordinates by taking into account the computed frame rateand drop mode as expressed by thettp:dropMode parameter.In this case, theContent Processor must create and maintain aSynthetic SMPTE Document Syncbase within which these timeexpressions are interpreted as further described in10.4 Time Intervals.

If a value ofdiscontinuous applies, then timeexpressions must not be converted to real timecoordinates, arithmetical operators (addition, multiplication) are notdefined on time expressions, and, consequently, any (well-formed)expression of a duration must be considered to be invalid.

6.2.7 ttp:pixelAspectRatio

Thettp:pixelAspectRatio attribute may be used by a content authorto express the aspect ratio of non-square pixels in the production of content thatmakes use of pixel coordinates.

If specified, the value of this attribute must adhere to the following syntax:

ttp:pixelAspectRatio  : width height                            //width != 0;height != 0width | height  :<digit>+

If not specified, then square pixels (i.e., aspect ratio 1:1) must be assumed to apply.If specified, then both width and height must be non-zero.

Attp:pixelAspectRatio attribute is considered to be significant onlywhen specified on thett element.

6.2.8 ttp:profile

Thettp:profile attribute may be used by a content authorto express the profile of the Timed Text Markup Language (TTML) usedin aDocument Instance.

If specified, the value of this attribute must adhere to thexsd:anyURI data type defined by[XML Schema Part 2],§3.2.17, and, further, must specify aprofile designator in accordance with5.2 Profiles.

Attp:profileattribute is considered to be significant only when specified on thett element.

6.2.9 ttp:subFrameRate

Thettp:subFrameRate attribute is used to specify the sub-frame rate of a relatedmedia object or the intrinsic sub-frame rate of aDocument Instance in case it is intendedto function as an independent media object.

If specified, the value of this attribute must adhere to the following syntax:

ttp:subFrameRate  :<digit>+                                //value > 0

The sub-frame rate that applies to aDocument Instance is used tointerpret time expressions that are expressed insub-framesas defined by10.3.1 <timeExpression>.

If themedia time base applies and the effective frame rate isintegral, a sub-frame is interpreted as a division of a frame of mediatime, such that if the sub-frame rate is specified asS, thena frame of media time is divided intoS intervals ofequal duration, where each interval is labeled as sub-frames,withs ∈ [0…S−1].

If not specified, the sub-frame rate must be considered to beequal to some application defined sub-frame rate, or if no application defined sub-frame rate applies, then one (1). If specified, then the sub-frame rate must be greater than zero (0).

Attp:subFrameRate attribute is considered to be significant onlywhen specified on thett element.

6.2.10 ttp:tickRate

Thettp:tickRate attribute is used to specify the tick rate of a relatedmedia object or the intrinsic tick rate of content of aDocument Instance in case it is intendedto function as an independent media object.

If specified, the value of this attribute must adhere to the following syntax:

ttp:tickRate  :<digit>+                                //value > 0

The tick rate that applies to aDocument Instance is used tointerpret time expressions that are expressed inticks byusing thet metric as defined by10.3.1 <timeExpression>.

If themedia time base applies,a tick is interpreted as an integral division of a second of mediatime, such that if the tick rate is specified asT, thena second of media time is divided intoT intervals ofequal duration, where each interval is labeled as tickt,witht ∈ [0…T−1].

If not specified, then if a frame rate is specified, the tick ratemust be considered to be the effective frame rate multiplied by thesub-frame rate (i.e., ticks are interpreted as sub-frames); or, if noframe rate is specified, the tick rate must be considered to be one (1)tick per second of media time. If specified, then the tick ratemust not be zero (0).

Attp:tickRate attribute is considered to be significant onlywhen specified on thett element.

6.2.11 ttp:timeBase

Thettp:timeBase attribute is used to specify thetemporal coordinate system by means of which time expressions areinterpreted in aDocument Instance.

If specified, the value of this attribute must adhere to the following syntax:

ttp:timeBase  : "media"  | "smpte"  | "clock"

If the time base is designated asmedia, then a timeexpression denotes a coordinate in some media object's time line,where the media object may be an external media object with which thecontent of aDocument Instance is to be synchronized, or it maybe the content of aDocument Instance itself in a case wherethe timed text content is intended to establish an independent timeline.

If the time base is designated assmpte,then a time expression denotes a[SMPTE 12M] timecoordinate with which the content of aDocument Instance is tobe synchronized. In this case, the value of thettp:markerMode andttp:dropMode parameters apply, as defined by6.2.6 ttp:markerMode and6.2.3 ttp:dropMode, respectively.

If the time base is designated asclock, then the timeexpression denotes a coordinate in some real-world time line asestablished by some real-time clock, such as the local wall-clock timeor UTC (Coordinated Universal Time) or GPS (Global Positioning System)time lines.

If not specified, the default time base must be considered to bemedia.

Attp:timeBase attribute is considered to be significant onlywhen specified on thett element.

When operating with eithermedia orsmptetime bases, a diachronic presentation of aDocument Instance maybe subject to transformations of the controlling time line, such astemporal reversal, dilation (expansion), or constriction(compression); however, when operating with theclocktime base, no transformations are permitted, and diachronicpresentation proceeds on a linear, monotonically increasing time linebased on the passage of real time.

7.1.1 tt

Thett element serves as the root document element of aDocument Instance.

Thett element accepts as its children zero or onehead element followed byzero or onebody element.

<tttts:extent = stringxml:id = IDxml:lang = stringxml:space = (default|preserve) : default  {any attribute in TT Parameter namespace}  {any attribute not in default or any TT namespace}>Content:head?,body?</tt>

TheRoot Temporal Extent, i.e., the time interval over which aDocument Instance is active, has an implicit duration that is equal to theimplicit duration of thebody element of the document, if thebody element is present, or zero, if thebody element is absent.

If thetts:extent attribute is specified on thettelement, then it must adhere to8.2.7 tts:extent, in which case itspecifies the spatial extent of theRoot Container Region inwhich content regions are located and presented. If notts:extentattribute is specified, then the spatial extent of theRoot Container Region isconsidered to be determined by theDocument Processing Context.The origin of theRoot Container Region is determined by theDocument Processing Context.

Anxml:lang attribute must be specified on thett element.If the attribute value is empty, it signifies that there is no default language that appliesto the text contained within theDocument Instance.

If noxml:space attribute is specified upon thett element, then it mustbe considered as if the attribute had been specified with a value ofdefault.

7.1.2 head

Thehead element is a container element used to groupheader matter, including metadata,profile, styling, and layout information.

Thehead element accepts as its children zero or moreelements in theMetadata.class element group,followed by zero or more elements in theParameters.class element group,followed by zero or onestyling element,followed by zero or onelayout element.

Any metadata specified by children in theMetadata.classelement group applies semantically to theDocument Instance as awhole, and not just thehead element.

Any parameters specified by children in theParameters.classelement group applies semantically to theDocument Instance as awhole, and not just thehead element.

Astyling child element is used to specify style constructsthat are referenced from other style constructs, by layout constructs, and byContent elements.

Alayout child element is used to specify layout constructs thatare referenced byContent elements.

<headxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Parameters.class*,styling?,layout?</head>

To the extent that time semantics apply to the content of thehead element, the implied time interval of this element isdefined to be coterminous with theRoot Temporal Extent.

7.1.3 body

Thebody element functions as a logical container and a temporalstructuring element for a sequence of textual content units represented aslogical divisions.

Thebody element accepts as its children zero or moreelements in theMetadata.class element group,followed by zero or moreelements in theAnimation.class element group,followed byzero or morediv elements.

Any metadata specified by children in theMetadata.classelement group applies semantically to thebody element and its descendants as a whole.

Any animation elements specified by children in theAnimation.classelement group apply semantically to thebody element.

<bodybegin =<timeExpression>dur =<timeExpression>end =<timeExpression>region = IDREFstyle = IDREFStimeContainer = (par|seq)xml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Metadata namespace}  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Animation.class*,div*</body>

An author may specify a temporal interval for abody element usingthebegin,dur, andend attributes. If the begin pointof this interval remains unspecified, then the begin point is interpreted as the beginningpoint of theRoot Temporal Extent. Similarly, if the end point of this interval remains unspecified, then theend point is interpreted as the ending point of theRoot Temporal Extent.

If relative begin or end times are specified on thebodyelement, then these times are resolved by reference to the beginning andending time of theRoot Temporal Extent.

If theRoot Temporal Extent is shorter than the computed duration of thebody element, then the active time interval of abody element istruncated to the active end point of theRoot Temporal Extent.

An author may associate a set of style properties with abody element by means of either thestyleattribute or inline style attributes or a combination thereof.

If notimeContainer attribute is specified on abody element, then it must be interpreted as havingparalleltime containment semantics.

7.1.4 div

Thediv element functions as a logical container and a temporalstructuring element for a sequence of textual content units represented aslogical sub-divisions or paragraphs.

Thediv element accepts as its children zero or moreelements in theMetadata.class element group,followed by zero or moreelements in theAnimation.class element group,followed byzero or morediv orp elements.

Any metadata specified by children in theMetadata.classelement group applies semantically to thediv element and its descendants as a whole.

Any animation elements specified by children in theAnimation.classelement group apply semantically to thediv element.

<divbegin =<timeExpression>dur =<timeExpression>end =<timeExpression>region = IDREFstyle = IDREFStimeContainer = (par|seq)xml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Metadata namespace}  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Animation.class*,Block.class*</div>

An author may associate a set of style properties with adiv element by means of eitherthestyle attribute or inline style attributes or a combination thereof.

If notimeContainer attribute is specified onadiv element, then it must be interpreted as havingparallel time containment semantics.

7.1.5 p

Ap element represents a logical paragraph, serving asa transition between block level and inline level formatting semantics.

Thep element accepts as its children zero or moreelements in theMetadata.class element group,followed by zero or moreelements in theAnimation.class element group,followed byzero or more intermixedspan elements,br elements,or text nodes.

Any metadata specified by children in theMetadata.classelement group applies semantically to thep element and its descendants as a whole.

Any animation elements specified by children in theAnimation.classelement group apply semantically to thep element.

<pbegin =<timeExpression>dur =<timeExpression>end =<timeExpression>region = IDREFstyle = IDREFStimeContainer = (par|seq)xml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Metadata namespace}  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Animation.class*,Inline.class*</p>

An author may associate a set of style properties with ap element by means of either thestyleattribute or inline style attributes or a combination thereof.

If notimeContainer attribute is specified onap element, then it must be interpreted as havingparallel time containment semantics.

If a sequence of children of ap elementconsists solely of character information items, then that sequence mustbe considered to be ananonymous span for the purpose ofapplying style properties that apply tospan elements.

7.1.6 span

Thespan element functions as a logical container and a temporalstructuring element for a sequence of textual content units having inlinelevel formatting semantics.

When presented on a visual medium, aspan element is intended togenerate a sequence of inline areas, each containing one or more glyph areas.

Thespan element accepts as its children zero or moreelements in theMetadata.class element group,followed by zero or moreelements in theAnimation.class element group,followed byzero or more intermixedspan elements,br elements,or text nodes.

Any metadata specified by children in theMetadata.classelement group applies semantically to thespan element and its descendants as a whole.

Any animation elements specified by children in theAnimation.classelement group apply semantically to thespan element.

<spanbegin =<timeExpression>dur =<timeExpression>end =<timeExpression>region = IDREFstyle = IDREFStimeContainer = (par|seq)xml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Metadata namespace}  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Animation.class*,Inline.class*</span>

An author may associate a set of style properties with aspan element by means of either thestyleattribute or inline style attributes or a combination thereof.

If notimeContainer attribute is specified onaspan element, then it must be interpreted as havingparallel time containment semantics.

7.1.7 br

Thebr element denotes an explicit line break.

Any metadata specified by children in theMetadata.classelement group applies semantically to thebr element and its descendants as a whole.

Any animation elements specified by children in theAnimation.classelement group apply semantically to thebr element.

<brstyle = IDREFSxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Metadata namespace}  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Animation.class*</br>

When presented on a visual medium, the presence of abr element must beinterpreted as a forced line break.

7.2.1 xml:id

Thexml:id attribute is used as defined by[XML ID].

Thexml:id attribute may be used with any element in thecore vocabulary catalog.

7.2.2 xml:lang

Thexml:lang attribute is used as defined by[XML 1.0], §2.12,Language Identification.

Thexml:lang attribute must be specified on thettelement and may be specified by an instance of any other element typein the core vocabulary catalog except parameter vocabulary.

7.2.3 xml:space

Thexml:space attribute is used as defined by[XML 1.0], §2.10,White Space Handling.

Thexml:space attribute may be used with any element inthe core vocabulary catalog except parameter vocabulary.

The semantics of the valuedefault are fixed to mean thatwhen performing presentation processing of aDocument Instance asdescribed by9.3.4 Synchronic Flow Processing,processing must occur asif the following properties were specified on the affectedelements of an equivalent intermediate XSL-FO document:

• suppress-at-line-break="auto"

• linefeed-treatment="treat-as-space"

• white-space-collapse="true"

• white-space-treatment="ignore-if-surrounding-linefeed"

Similarly, the semantics of the valuepreserve are fixed to mean thatwhen performing presentation processing, processing must occur asif the following properties were specified on the affectedelements of an equivalent intermediate XSL-FO document:

• suppress-at-line-break="retain"

• linefeed-treatment="preserve"

• white-space-collapse="false"

• white-space-treatment="preserve"

When performing other types of processing intended to eventuallyresult in a visual presentation by means other than those describedin this specification, the semantics of space collapsing andpreservation as described above should be respected. For other typesof processing, the treatment of thexml:space attributeis processor dependent, but should respect the semantics describedabove if possible.

8.1.1 styling

Thestyling element is a container element used to groupstyling matter, including metadata that applies to styling matter.

Thestyling element accepts as its children zero or moreelements in theMetadata.class element group, followed byzero or morestyle elements.

<stylingxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content:Metadata.class*,style*</styling>

To the extent that time semantics apply to the content of thestyling element, the implied time interval of this element isdefined to be coterminous with theRoot Temporal Extent.

8.1.2 style

Thestyle element is used to definea set of style specifications expressed as aspecified style set in accordance with8.4.4.2 Specified Style Set Processing.

<stylestyle = IDREFSxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content: EMPTY</style>

If astyle element appears as a descendant of aregion element, then thestyle element must beignored for the purpose of computing referential styles as defined by8.4.1.2 Referential Styling and8.4.1.3 Chained Referential Styling.

Note:

This specification makes use oflowerCamelCased localnames for style attributes thatare based upon like-named properties defined by[XSL 1.1].This convention is likewise extended to token values of suchproperties.

Note:

A style property may be expressed as a specified attribute on anyContent element typeindependently of whether the property applies to thatelement type. This capability permits the expression of an inheritablestyle property on ancestor elements to which the propertydoes not apply.

Note:

Due to the general syntax of this specification (and the schemas it references) with respectto how style attributes are specified, particularly for the purpose of supporting inheritance,it is possible for an author to inadvertently specify a non-inheritable style attribute onan element that applies neither to that element or any of its descendants while still remainingconformant from a content validity perspective. Content authors may wish to make use of TTMLcontent verification tools that detect and warn about such usage.

8.2.1 style

Thestyle attribute is used by referential style associationto reference one or morestyle elements each of which define a style (property) set.

Thestyle attribute may be specified by an instance of the followingelement types:

• body

• br

• div

• p

• region

• span

• style

If specified, the value of astyle attribute mustadhere to theIDREFS data type defined by[XML Schema Part 2],§ 3.3.10, and, furthermore, each IDREF must reference astyle elementwhich has astyling element as an ancestor.

If the same IDREF,ID₁, appears more than one time in the value of astyleattribute, then there should be an intervening IDREF,ID₂, whereID₂ is not equal toID₁.

8.2.2 tts:backgroundColor

Thetts:backgroundColor attribute is used to specify a style property thatdefines the background color of a region or an area generated by content flowed into a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

Thetts:backgroundColor style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="306px 114px"/>  <styletts:backgroundColor="red"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:padding="3px 40px"/></region>...<p region="r1"tts:backgroundColor="purple" tts:textAlign="center">  Twinkle, twinkle, little bat!<br/>  How <spantts:backgroundColor="green">I wonder</span> where you're at!</p>

Example Rendition – Background Color

8.2.3 tts:color

Thetts:color attribute is used to specify a style property thatdefines the foreground color of marks associated with an area generated by content flowed into a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

The initial value of thetts:color propertyis considered to be implementation dependent. In the absence ofend-user preference information, a conformant presentation processorshould use an initial value that is highly contrastive to thebackground color of theRoot Container Region.

Thetts:color style is illustrated by the following example.

<region xml:id="r1">  <style tts:backgroundColor="black"/>  <styletts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/></region>...<p region="r1">  In spring, when woods are <spantts:color="green">getting green</span>,<br/>  I'll try and tell you what I mean.</p>

Example Rendition – Color

8.2.4 tts:direction

Thetts:direction attribute is used to specify a style property that, depending on the context of use,determines (1) the bidirectional paragraph level, or (2) the directionality of a bidirectional embedding or override.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

When applied to ap element, the computed value of this property explicitly establishes theparagraph level as specified by[UAX9], § 4.3, Higher Level ProtocolHL1.

When applied to aspan element (or anonymous span), the computed value of this property, in combination with the computed valueof thetts:unicodeBidi style property, determines the directionality of a bidirectional embedding or override as specified by[UAX9], § 4.3, Higher Level ProtocolHL3.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valueltr.

Thetts:direction style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="265px 84px"/>  <style tts:padding="5px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/></region>...<p region="r1">  Little birds are playing<br/>  Bagpipes on the shore,<br/>  <span tts:unicodeBidi="bidiOverride"tts:direction="rtl">where the tourists snore.</span></p>

Example Rendition – Direction

8.2.5 tts:display

Thetts:display attribute is used to specify a style property thatdefines whether an element is a candidate for layout and compositionin a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

If the value of this attribute isauto,then the affected element is a candidate for region layout andpresentation; however, if the value isnone, then theaffected element and its descendants must be considered ineligible for regionlayout and presentation.

Thetts:display style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="369px 119px"            tts:backgroundColor="black"            tts:color="white"            tts:displayAlign="before"            tts:textAlign="start"/></region>...<div region="r1">  <p dur="5s">    [[[    <spantts:display="none">      <set begin="1s" dur="1s"tts:display="auto"/>      Beautiful soup,    </span>    <spantts:display="none">      <set begin="2s" dur="1s"tts:display="auto"/>      so rich and green,    </span>    <spantts:display="none">      <set begin="3s" dur="1s"tts:display="auto"/>      waiting in a hot tureen!    </span>    ]]]  </p></div>

Example Rendition – Display

8.2.6 tts:displayAlign

Thetts:displayAlign attribute is used to specify a style property thatdefines the alignment of block areas in the block progression direction.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuebefore.

Thetts:displayAlign style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="128px 66px" tts:origin="0px 0px"       tts:backgroundColor="black" tts:color="white"/>  <styletts:displayAlign="before"/>  <style tts:textAlign="start"/></region><region xml:id="r2">  <style tts:extent="192px 66px" tts:origin="128px 66px"/>       tts:backgroundColor="green" tts:color="white"/>  <styletts:displayAlign="after"/>  <style tts:textAlign="start"/></region><region xml:id="r3">  <style tts:extent="128px 66px"/> style tts:origin="0px 132px"       tts:backgroundColor="black" tts:color="white"/>  <styletts:displayAlign="before"/>  <style tts:textAlign="start"/></region><region xml:id="r4">  <style tts:extent="192px 66px" tts:origin="128px 198px"/>       tts:backgroundColor="green" tts:color="white"/>  <styletts:displayAlign="after"/>  <style tts:textAlign="start"/></region>...<div>  <p region="r1">I sent a message to the fish:</p>  <p region="r2">I told them<br/> "This is what I wish."</p>  <p region="r3">The little fishes of the sea,</p>  <p region="r4">They sent an<br/> answer back to me.</p></div>

Example Rendition – Display Align

8.2.7 tts:extent

Thetts:extent attribute is used to specify thewidth andheight of a region area(which may be theRoot Container Region).

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If the value of this attribute consists of two<length>specifications, then they must be interpreted aswidthandheight, where the first specification is thewidth, and the second specification is theheight.

The<length> value(s) used to express extent must be non-negative.

If the value of this attribute isauto, then the computed valueof the style property must be considered to be the same as the extent of theRoot Container Region.

The extent of theRoot Container Region is determined either by atts:extent specified on thett element, ifpresent, or as described by7.1.1 tt if not present.Iftts:extent is specified on thett element, thenthe width and height must be expressed in terms of two<length> specifications,and these specifications must be expressed as non-percentage, definite lengths using pixel units.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the closest supported value.

Thetts:extent style is illustrated by the following example.

<region xml:id="r1">  <styletts:extent="330px 122px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/></region>...<p region="r1">  'Tis the voice of the Lobster:<br/>  I heard him declare,<br/>  "You have baked me too brown,<br/>  I must sugar my hair."</p>

Example Rendition – Extent

8.2.8 tts:fontFamily

Thetts:fontFamily attribute is used to specify a style property thatdefines the font family from which glyphs are selected for glyph areas generatedby content flowed into a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

If a computed value of the property associated with this attribute is not supported, then apresentation processor must attempt to map the computed font familyto a supported font family that has similar typographiccharacteristics, or, in the absence of such a mapping, it mustuse the valuedefault.

Thetts:fontFamily style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="474px 146px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="center"/>  <style tts:textAlign="start"/>  <styletts:fontFamily="proportionalSansSerif"/></region>...<div region="r1">  <p>    "The time has come," the Walrus said,<br/>    "to talk of many things:  </p>  <p tts:textAlign="end"tts:fontFamily="monospaceSerif">    Of shoes, and ships, and sealing wax,<br/>    Of cabbages and kings,  </p>  <p>    And why the sea is boiling hot,<br/>    and whether pigs have wings."  </p></div>

Example Rendition – Font Family

8.2.9 tts:fontSize

Thetts:fontSize attribute is used to specify a style propertythat defines the font size for glyphs that are selected for glyph areasgenerated by content flowed into a region.

This attribute may be specified by any element typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

The computed value of the property associated with this attribute consists of a 2-tuplethe entries of which denote the computed values of the width and height components of the font size respectively.

If a single<length> value is specified, then this length appliesequally to horizontal and vertical size of a glyph's EM square; if two<length> values are specified, then the first expresses the horizontalsize and the second expresses vertical size.

If horizontal and vertical sizes are expressed independently, then theunits of the<length> values must be the same.

Relative<length> valuesthat appear in this attribute, i.e., values expressed in percentage (%), cell (c), or EM (em) units,are resolved in relation to a referenced 2-dimensional size value consisting of two components, a width component anda height component.

When a single relative<length> value is specified, thenthis<length> is resolved in terms of the height component of the referenced value;when two relative<length> values are specified,the first<length> is resolved in terms of the width component of the referenced value andthe second<length> is resolved in terms of the height component of the referenced value.

If the relative unit is cell (c), then the referenced value is theComputed Cell Size.

If the relative unit is EM (em), then the referenced value is determined as if percentage unitswere used, where1em equals100%.

The<length> value(s) used to express font size must be non-negative.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the closest supported value.

Thetts:fontSize style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="299px 97px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="center"/>  <style tts:textAlign="center"/>  <style tts:fontFamily="proportionalSansSerif"/>  <styletts:fontSize="18px"/></region>...<p region="r1">  Then fill up the glasses<br/>  with treacle and ink,<br/>  Or anything else<br/>  that is <spantts:fontSize="24px">pleasant</span> to drink.</p>

Example Rendition – Font Size

8.2.10 tts:fontStyle

Thetts:fontStyle attribute is used to specify a style property thatdefines the font style to apply to glyphs that are selected for glyph areas generatedby content flowed into a region, where the mapping from fontstyle value to specific font face or style parameterization is not determinedby this specification.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

Use of the valueobliquedenotes a shear transformation (at an unspecifiedangle) in the inline progression dimension.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuenormal.

Thetts:fontStyle style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="331px 84px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/>  <style tts:fontFamily="proportionalSansSerif"/></region>...<p region="r1">  In autumn, when the leaves are brown,<br/>  Take pen and ink, and <spantts:fontStyle="italic">write it down.</span></p>

Example Rendition – Font Style

8.2.11 tts:fontWeight

Thetts:fontWeight attribute is used to specify a style propertythat defines the font weight to apply to glyphs that are selected for glyphareas generated by content flowed into a region, where the mapping from fontweight value to specific font face or weight parameterization is not determinedby this specification.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuenormal.

Thetts:fontWeight style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="376px 95px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="center"/>  <style tts:textAlign="center"/>  <style tts:fontFamily="proportionalSansSerif"/></region>...<p region="r1">  They told me you had been to her,<br/>  <spantts:fontWeight="bold">and mentioned me to him:</span><br/>  She gave me a good character<br/>  <spantts:fontWeight="bold">but said I could not swim.</span></p>

Example Rendition – Font Weight

8.2.12 tts:lineHeight

Thetts:lineHeight attribute is used to specify a style property thatdefines the inter-baseline separation between line areas generated by content flowed into a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If the value of this attribute isnormal, then theused value of this style property should be determined as follows:

1. LetP be thep element to which this style property applies.

2. LetFF be the computed value of thetts:fontFamilystyle property ofP.

3. LetFS be the computed value of thetts:fontSize style property ofP.

4. LetF0 be the first font obtained when sequentially mapping each font family inFF to a set of available fonts,where this set of available fonts is constrained as needed to satisfy the computed values of thetts:fontStyle andtts:fontWeightstyle properties ofP.

5. IfF0 is associated with font metrics that specify altitudeA, descentD, and line gapG,then setLH to the sum of scaled(A), scaled(D), and scaled(G),where scaled(X) denotes font metricX scaled according to font sizeFS.

6. Otherwise,LH is considered to be implementation dependent; however, in the absence of implementation specific requirements,LH is recommended to be set to 125% ofFS.

7. Set theused value of this style property toLH.

If specified as a<length>, then the length mustbe non-negative.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the closest supported value.

Thetts:lineHeight style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="255px 190px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="center"/>  <style tts:textAlign="start"/>  <style tts:fontFamily="proportionalSansSerif"/>  <style tts:fontSize="16px"/>  <styletts:lineHeight="32px"/></region>...<p region="r1">  He thought he saw an elephant,<br/>  That practised on a fife:<br/>  He looked again, and found it was<br/>  A letter from his wife.<br/>  "At length I realise," he said,<br/>  "The bitterness of Life."</p>

Example Rendition – Line Height

8.2.13 tts:opacity

Thetts:opacity attribute is used to specify a style property thatdefines the opacity (or conversely, the transparency)of marks associated with a region.

When presented onto a visual medium, the opacity of the region is applied uniformly and on a linear scaleto all marks produced by content targeted to theregion.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

Thetts:opacity style is illustrated by the following example.

<region xml:id="r1" dur="5s">  <set begin="0s" dur="1s"tts:opacity="1.00"/>  <set begin="1s" dur="1s"tts:opacity="0.75"/>  <set begin="2s" dur="1s"tts:opacity="0.50"/>  <set begin="3s" dur="1s"tts:opacity="0.25"/>  <set begin="4s" dur="1s"tts:opacity="0.00"/>  <style tts:extent="304px 77px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/></region>...<p region="r1">  The sun was shining on the sea</p>

Example Rendition – Opacity

8.2.14 tts:origin

Thetts:origin attribute is used to specify thex andy coordinates of the origin of aregion area with respect to the origin of theRoot Container Region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If the value of this attribute consists of two<length> specifications,then they must be interpreted asx andy coordinates, where the first specificationis thex coordinate, and the second specification is they coordinate.

If the value of this attribute isauto, then the computed valueof the style property must be considered to be the same as the origin of theRoot Container Region.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the closest supported value.

Thetts:origin style is illustrated by the following example.

<region xml:id="r1">  <styletts:origin="40px 40px"/>  <style tts:extent="308px 92px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="center"/>  <style tts:textAlign="center"/></region>...<p region="r1">  "To dine!" she shrieked in dragon-wrath.<br/>  "To swallow wines all foam and froth!<br/>   To simper at a table-cloth!"</p>

Example Rendition – Origin

8.2.15 tts:overflow

Thetts:overflow attribute is used to specify a style property thatdefines whether a region area is clipped or not if the descendant areas of the region overflowits extent.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If the value of this attribute isvisible, then content shouldnot be clipped outside of the affected region, and region composition and layoutmust be performed as if the region's width and height wereunconstrained,but witha well-defined origin. If the value ishidden, then content shouldbe clipped outside of the affected region.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuehidden.

Thetts:overflow style is illustrated by the following example.

<?xml version="1.0"?><tt xmlns="http://www.w3.org/ns/ttml"    xmlns:tts="http://www.w3.org/ns/ttml#styling"    xml:lang="en"    tts:extent="320px 240px">  <head>    <styling>      <style xml:id="s1" tts:backgroundColor="black"             tts:padding="6px"/>      <style xml:id="s2" tts:color="red" tts:backgroundColor="white"             tts:wrapOption="noWrap" tts:fontFamily="proportionalSansSerif"             tts:fontSize="10px"/>    </styling>    <layout>      <region xml:id="r1" tts:extent="100px 40px"              tts:origin="20px 20px" tts:overflow="visible"/>      <region xml:id="r2" tts:extent="100px 40px"              tts:origin="20px 180px" tts:overflow="hidden"/>    </layout>  </head>  <body>    <div>      <p region="r1">        "But wait a bit," the Oysters cried,<br/>        "Before we have our chat;      </p>      <p region="r2">        For some of us are out of breath,<br/>        And all of us are fat!"      </p>    </div>  </body></tt>

Example Rendition – Overflow

8.2.16 tts:padding

Thetts:padding attribute is used to specify padding (or inset)space on all sides of a region area.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If the value of this attribute consists of one<length> specification,then that length applies to all edges of the affected areas. If the valueconsists of two<length> specifications, then the first applies to thebefore and after edges, and the second applies to the start and end edges.If three<length> specifications are provided, then the first applies to thebefore edge, the second applies to the start and end edges, and the third appliesto the after edge.If four<length> specifications are provided, then they apply to before, end,after, and start edges, respectively.

The<length> value(s) used to express padding must be non-negative.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the closest supported value.

Thetts:padding style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="446px 104px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/>  <styletts:padding="10px 40px"/></region>...<p region="r1" tts:backgroundColor="red">  Just the place for a Snark! I have said it twice:<br/>  That alone should encourage the crew.<br/>  Just the place for a Snark! I have said it thrice:<br/>  What I tell you three times is true.</p>

When rendering an area to which padding applies, the background color thatapplies to the area is rendered into the padded portion of the area.

Example Rendition – Padding

8.2.17 tts:showBackground

Thetts:showBackground attribute is used to specifyconstraints on when the background color of a region is intended to bepresented.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If the value of this attribute isalways, then thebackground color of a region is always rendered when performing presentationprocessing on a visual medium; if the value iswhenActive,then the background color of a region is rendered only when somecontent is flowed into the region.

A region satisfies thewhenActive case if (1) it is aTemporally Active Region and (2) content is selected into the region, where that content is alsoTemporally Active.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuealways.

Thetts:showBackground style is illustrated by the following example.

<region xml:id="r1">  <style tts:origin="0px 0px"/>  <style tts:extent="265px 100px"/>  <style tts:backgroundColor="black"/>  <styletts:showBackground="always"/>  <style tts:color="white"/>  <style tts:displayAlign="before"/>  <style tts:textAlign="start"/></region><region xml:id="r2">  <style tts:origin="205px 60px"/>  <style tts:extent="290px 100px"/>  <style tts:backgroundColor="red"/>  <style tts:color="white"/>  <style tts:displayAlign="before"/>  <style tts:textAlign="end"/>  <styletts:showBackground="whenActive"/></region>

8.2.18 tts:textAlign

Thetts:textAlign attribute is used to specify a style property thatdefines how inline areas are aligned within a containing block area in the inline progressiondirection.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuestart.

Thetts:textAlign style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="355px 43px"/>  <style tts:origin="0px 0px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <styletts:textAlign="start"/></region><region xml:id="r2">  <style tts:extent="355px 43px"/>  <style tts:origin="0px 47px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <styletts:textAlign="end"/></region>...<p region="r1">  Beware the Jabberwock, my son!<br/>  The jaws that bite, the claws that catch!</p><p region="r2">  Beware the Jubjub bird, and shun<br/>  The frumious Bandersnatch!</p>

Example Rendition – Text Align

8.2.19 tts:textDecoration

Thetts:textDecoration attribute is used to specify a style property thatdefines a text decoration effect to apply to glyph areas or other inlineareas that are generated by content flowed into a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of thisstyle property, each character child of ap element isconsidered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuenone.

Thetts:textDecoration style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="385px 82px"/>  <style tts:origin="0px 0px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:padding="5px 2px"/>  <styletts:textDecoration="underline"/></region>...<p region="r1">  The sea was wet<spantts:textDecoration="noUnderline"> as </span>wet  <spantts:textDecoration="noUnderline">    could be,<br/>    The sand was dry as dry.<br/>    <spantts:textDecoration="lineThrough">There weren't any</span>    You <spantts:textDecoration="lineThrough">couldn't</span>    could not see a cloud<br/>    Because no cloud was in the sky.  </span></p>

Example Rendition – Text Decoration

8.2.20 tts:textOutline

Thetts:textOutline attribute is used to specify a style property thatdefines a text outline effect to apply to glyphs that are selected for glyph areas generatedby content flowed into a region.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

The value of this attribute consists of an optional<color> termfollowed by one or two<length> terms. If acolor term ispresent, then it denotes the outline color; if nocolor term ispresent, the computed value of thetts:color applies. The firstlength term denotes the outline thickness and the second lengthterm, if present, indicates the blur radius.

When a relative<length> value is specified for outline thickness or blur radius, then it is resolved in terms of the height componentof the referenced font size orComputed Cell Size.

The<length> value(s) used to express thickness and blur radius must be non-negative.

If no blur radius is specified, i.e., only one<length> term is present,then the computed value of0px applies.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuenone.

Thetts:textOutline style is illustrated by the followingexample.

<region xml:id="r1">  <style tts:backgroundColor="transparent"/>  <style tts:color="yellow"/>  <styletts:textOutline="black 2px 0px"/>  <style tts:fontFamily="proportionalSansSerif"/>  <style tts:fontSize="24px"/></region>...<p>  How doth the little crocodile<br/>  Improve its shining tail,<br/>  And pour the waters of the Nile<br/>  On every golden scale!<br/>  How cheerfully he seems to grin,<br/>  How neatly spreads his claws,<br/>  And welcomes little fishes in,<br/>  With gently smiling jaws!</p>

Example Rendition – Text Outline

8.2.21 tts:unicodeBidi

Thetts:unicodeBidi attribute is used to specify a style property thatdefines a directional embedding or override according tothe Unicode bidirectional algorithm.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuenormal.

Thetts:unicodeBidi style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="265px 84px"/>  <style tts:padding="5px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:textAlign="center"/></region>...<p region="r1">  Little birds are playing<br/>  Bagpipes on the shore,<br/>  <spantts:unicodeBidi="bidiOverride" tts:direction="rtl">where the tourists snore.</span></p>

Example Rendition – Unicode Bidirectionality

8.2.22 tts:visibility

Thetts:visibility attribute is used to specify a style property thatdefines whether generated areas are visible or not when rendered on a visualpresentation medium.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

Thetts:visibility style has no affect on content layout orcomposition, but merely determines whether composed content is visible or not.

If the computed value of the property associated with this attribute isvisible, then areas generatedby this element are rendered visible when presented on a visual medium. If the computed value ishidden, then they are notrendered visible, i.e., they are hidden; notwithstanding the foregoing, a descendant element of a hidden element is renderedvisible if the computed value of this property isvisible on the descendant.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuevisible.

Thetts:visibility style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="398px 121px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style/></region>...<p region="r1" dur="4s">  <spantts:visibility="hidden">    <set begin="1s"tts:visibility="visible"/>    Curiouser  </span>  <spantts:visibility="hidden">    <set begin="2s"tts:visibility="visible"/>    and  </span>  <spantts:visibility="hidden">    <set begin="3s"tts:visibility="visible"/>    curiouser!  </span></p>

Example Rendition – Visibility

8.2.23 tts:wrapOption

Thetts:wrapOption attribute is used to specify a style property thatdefines whether or not automatic line wrapping (breaking) applies within the context ofthe affected element.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

For the purpose of determining applicability of this style property,each character child of ap element is considered to be enclosed in an anonymousspan.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuewrap.

Thetts:wrapOption style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="192px 117px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <style tts:displayAlign="after"/>  <style tts:overflow="hidden"/>  <styletts:wrapOption="noWrap"/></region>...<p>  I'll tell thee everything I can:<br/>  There's little to relate.<br/>  I saw an aged aged man,<br/>  A-sitting on a gate.</p>

Example Rendition – Wrap Option

8.2.24 tts:writingMode

Thetts:writingMode attribute is used to specify a style property thatdefines the block and inline progression directions to be used for the purpose ofstacking block and inline areas within a region area.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the valuelrtb.

Thetts:writingMode style is illustrated by the following example.

<region xml:id="r1">  <style tts:extent="50px 570px"/>  <style tts:origin="0px 0px"/>  <style tts:padding="10px 3px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <styletts:writingMode="tbrl"/></region><region xml:id="r2">  <style tts:extent="310px 50px"/>  <style tts:origin="70px 120px"/>  <style tts:padding="10px 3px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <styletts:writingMode="rltb"/></region>...<p region="r1">  I sometimes dig for buttered rolls,<br/>  Or set limed twigs for crabs:</p><p region="r2" tts:direction="rtl" tts:unicodeBidi="bidiOverride">  I sometimes search the grassy knolls for the wheels of Hansom-cabs.</p>

Example Rendition – Writing Mode

8.2.25 tts:zIndex

Thetts:zIndex attribute is used to specify a style property thatdefines the front-to-back ordering of region areas in the case that they overlap.

This attribute may be specified by anyelement typethat permits use of attributes in the TT Style Namespace; however, this attribute appliesas a style property only to those element types indicated in the following table.

If two areas are associated with the same Z-index value, then, if those areasoverlap in space, the area(s) generated by lexically subsequent elements must berendered over area(s) generated by lexically prior elements, where lexicalorder is defined as the postorder traversal of aDocument Instance.

Thett element is considered to establish the root of the stacking context, as defined by[XSL 1.1], § 7.30.18.

If a computed value of the property associated with this attribute is not supported,then a presentation processor must use the closest supported value.

Thetts:zIndex style is illustrated by the following example.

<region xml:id="r1">  <style tts:origin="0px 0px"/>  <style tts:extent="400px 100px"/>  <style tts:padding="5px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <styletts:zIndex="0"/></region><region xml:id="r2">  <style tts:origin="100px 60px"/>  <style tts:extent="400px 100px"/>  <style tts:padding="5px"/>  <style tts:backgroundColor="red"/>  <style tts:color="white"/>  <style tts:textAlign="end"/>  <styletts:zIndex="1"/></region><region xml:id="r3">  <style tts:origin="0px 120px"/>  <style tts:extent="400px 100px"/>  <style tts:padding="5px"/>  <style tts:backgroundColor="black"/>  <style tts:color="white"/>  <styletts:zIndex="2"/></region><region xml:id="r4">  <style tts:origin="100px 180px"/>  <style tts:extent="400px 100px"/>  <style tts:padding="5px"/>  <style tts:backgroundColor="red"/>  <style tts:color="white"/>  <style tts:textAlign="end"/>  <styletts:zIndex="3"/></region>...<p region="r1">  I passed by his garden, and marked, with one eye,<br/>  How the Owl and the Panther were sharing a pie.</p><p region="r2">  The Panther took pie-crust, and gravy, and meat,<br/>  While the Owl had the dish as its share of the treat.</p><p region="r3">  When the pie was all finished, the Owl, as a boon,<br/>  Was kindly permitted to pocket the spoon:</p><p region="r4">  While the Panther received knife and fork<br/>  with a growl,<br/>  And concluded the banquet by...</p>

Example Rendition – Z Index

8.3.1 <alpha>

An <alpha> expression is used to express an opacity value,where0 means fully transparent and 1 means fully opaque.

<alpha>  :float

In the above syntax representation, the syntactic elementfloat must adhere to the lexicalrepresentation defined by[XML Schema Part 2] §3.2.4.1. If the value represented is less than 0.0,then it must be interpreted as equal to 0.0; similarly, if the valuerepresented is greater than 1.0, then it must be interpreted as1.0. The value NaN must be interpreted as 0.0.

A specified value for <alpha> should not beNaN,less than 0, or greater than 1.

If a presentation processor does not support a specific,valid opacity value, then it must interpret it as being equal to theclosest supported value.

8.3.2 <color>

A <color> expression is used to specify a named color, exact RGB color triple,or exact RGBA color tuple, where the alpha component, if expressed,is maximum (255) at 100% opacityand minimum (0) at 0% opacity, and where the applicable color space isdefined by[SRGB].

<color>  : "#" rrggbb  | "#" rrggbbaa  | "rgb(" r-value "," g-value "," b-value ")"  | "rgba(" r-value "," g-value "," b-value "," a-value ")"  |<namedColor>rrggbb  :<hexDigit>{6}rrggbbaa  :<hexDigit>{8}r-value | g-value | b-value | a-value  : component-valuecomponent-value  : non-negative-integer                    // valid range: [0,255]non-negative-integer  :<digit>+

When expressing RGB component values, these values are consideredtonot be premultiplied by alpha.

For the purpose of performing presentation processing such thatnon-opaque or non-transparent alpha or opacity values apply, then thesemantics of compositing functions are defined with respect to the use ofthe[SRGB] color space for both inputs and outputs ofthe composition function.

If a presentation processor does not support a specific,valid color or alpha value, then it must interpret it as being equalto the closest supported value.

8.3.3 <digit>

A <digit> is used to express integers and other types of numbers or tokens.

<digit>  : "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

8.3.4 <duration>

This section is non-normative.

8.3.5 <familyName>

A <familyName> expression specifies a font family name.

<familyName>  : unquoted-string  | quoted-stringunquoted-string  : identifier ( lwsp identifier )*lwsp  : ( ' ' | '\t' | '\n' | '\r' )+identifier  : [-]? identifier-start identifier-following*identifier-start  : [_a-zA-Z]  | non-ascii-or-c1  | escapeidentifier-following  : [_a-zA-Z0-9-]  | non-ascii-or-c1  | escapenon-ascii-or-c1  : [^\0-\237]escape  : '\\'charquoted-string  : double-quoted-string  | single-quoted-stringdouble-quoted-string  : '"' ( [^"\\] | escape )+ '"'single-quoted-string  : "'" ( [^'\\] | escape )+ "'"

In addition to adhering to the syntax rules specified above, the following semantic rules apply:

• the semantic value of a <familyName> expression is the semantic value of itsunquoted-string orquoted-stringnon-terminal, according to whichever applies;

• the semantic value of anunquoted-string non-terminal is a pair<quoted,content>,wherequoted is a booleanfalse, andwherecontent is the result of appending the value of eachidentifiernon-terminal, in lexical order, where the value of each identifier is preceded by a single SPACE (U+0020) character if it is not the firstidentifier;

• the semantic value of aquoted-string non-terminal is a pair<quoted,content>,wherequoted is a booleantrue, andwherecontent is the unquoted content of the quoted string, i.e., the sequence of characters between the delimiting quotes.

• the semantic value of anescape non-terminal is the value of the escapedchar;

• a <familyName> that takes the form of anunquoted-string that contains anidentifier thatstarts with two- HYPHEN-MINUS (U+002D) characters must be considered to be invalid;

• a <familyName> that takes the form of anunquoted-string that contains a singleidentifier thatmatches (by case sensitive comparison) a <genericFamilyName> must be interpreted as that <genericFamilyName>;

• a <familyName> that takes the form of aquoted-string whose content (unquoted value)matches (by case sensitive comparison) a <genericFamilyName> must not be interpreted as that <genericFamilyName>, but asthe actual name of a non-generic font family.

8.3.6 <genericFamilyName>

A <genericFamilyName> expression specifies a font family using a generaltoken that indicates a class of font families.

The resolution of a generic family name to a concrete font instance is considered tobe implementation dependent, both in the case of content authoring and content interpretation.

<genericFamilyName>  : "default"  | "monospace"  | "sansSerif"  | "serif"  | "monospaceSansSerif"  | "monospaceSerif"  | "proportionalSansSerif"  | "proportionalSerif"

The mapping between a generic (font) family name and an actual font is notdetermined by this specification; however, thedistinction of monospace versus proportional and serif versus sans-serifshould be maintained if possible when performing presentation.

If a generic (font) family name ofmonospace is specified,then it may be interpreted as equivalent to eithermonospaceSansSeriformonospaceSerif. The generic family namessansSerifandserif are to be interpreted as equivalent toproportionalSansSerifandproportionalSerif, respectively.

If the generic family namedefault is specified (or implied byan initial value), then its typographic characteristics are considered to be implementationdependent; however, it is recommended that this default font family be mapped toa monospaced, sans-serif font.

8.3.7 <hexDigit>

A <hexDigit> is used to express integers and other types of numbers or tokensthat employ base 16 arithmetic.

For the purpose of parsing, a distinction must not be made between lower and upper case.

<hexDigit>  :<digit>  | "a" | "b" | "c" | "d" | "e" | "f"  | "A" | "B" | "C" | "D" | "E" | "F"

8.3.8 <integer>

An <integer> expression is used to express an arbitrary, signed integral value.

<integer>  : ( "+" | "-" )?<digit>+

8.3.9 <length>

A <length> expression is used to express either a coordinate component of pointin a cartesian space or a distance between two points in a cartesian space.

<length>  : scalar  | percentagescalar  : number unitspercentage  : number "%"sign  : "+" | "-"number  : sign? non-negative-numbernon-negative-number  : non-negative-integer  | non-negative-realnon-negative-integer  :<digit>+non-negative-real  :<digit>* "."<digit>+units  : "px"  | "em"  | "c"                                     // abbreviation of "cell"

It is an error to omit the units component of a scalar lengthvalue.

The semantics ofthe unit of measurepx (pixel) are as defined by[XSL 1.1], § 5.9.13.

When specified relative to a font whose size is expressed as a single lengthmeasure or as two length measures of equal length, the unit of measureem is considered to beidentical to that defined by[XSL 1.1], § 5.9.13;however, when specified relative to a font whose size is expressed astwo length measures of non-equal lengths, then oneem isequal to the inline progression dimension of the anamorphicallyscaled font when used to specify lengths in the inline progressiondirection and equal to the block progression dimension of the scaledfont when used to specify lengths in the block progression direction.

The semantics of the unit of measurec (cell) aredefined by the parameter6.2.1 ttp:cellResolution.

8.3.10 <namedColor>

A <namedColor> is used to express an RGBA color with a convenient name, and where the applicable color space isdefined by[SRGB].

For the purpose of parsing, a distinction must not be made between lower and upper case.

<namedColor>  : "transparent"                           // #00000000  | "black"                                 // #000000ff  | "silver"                                // #c0c0c0ff  | "gray"                                  // #808080ff  | "white"                                 // #ffffffff  | "maroon"                                // #800000ff  | "red"                                   // #ff0000ff  | "purple"                                // #800080ff  | "fuchsia"                               // #ff00ffff  | "magenta"                               // #ff00ffff (= fuchsia)  | "green"                                 // #008000ff  | "lime"                                  // #00ff00ff  | "olive"                                 // #808000ff  | "yellow"                                // #ffff00ff  | "navy"                                  // #000080ff  | "blue"                                  // #0000ffff  | "teal"                                  // #008080ff  | "aqua"                                  // #00ffffff  | "cyan"                                  // #00ffffff (= aqua)

8.3.11 <quotedString>

This section is non-normative.

8.3.12 <string>

This section is non-normative.

Note:

The semantics of style resolution employed here are based upon[XSL 1.1], § 5.

8.4.1 Style Association

Style association is a sub-process of8.4.4 Style Resolution Processing used to determine thespecified style set of each content andlayout element.

Style matter may be associated with content and layout matter in a number of ways:

• inline styling

• referential styling

• chained referential styling

In addition to the above, style matter may be associated with layout matter using:

• nested styling

<ptts:color="white">White 1 <spantts:color="yellow">Yellow</span> White 2</p>

<stylexml:id="s1" tts:color="white"/><stylexml:id="s2" tts:color="yellow"/>...<pstyle="s1">White 1 <spanstyle="s2">Yellow</span> White 2</p>

<stylexml:id="s1" tts:color="white" tts:fontFamily="monospaceSerif"/><stylexml:id="s2"style="s1" tts:color="yellow"/>...<pstyle="s1">White Monospace</p><pstyle="s2">Yellow Monospace</p>

<region xml:id="r1"><style tts:extent="128px 66px"/><style tts:origin="0px 0px"/><style tts:displayAlign="center"/></region>

8.4.2 Style Inheritance

Style inheritance is a sub-process of8.4.4 Style Resolution Processing used to determine thespecified style set of each content andlayout element.

Styles are further propagated to content matterusing:

• content style inheritance

• region style inheritance

For the purpose of determining inherited styles, the element hierarchy ofan intermediate synchronic document form of aDocument Instance must be used, wheresuch intermediate forms are defined by9.3.3 Intermediate Synchronic Document Construction.

<ptts:fontFamily="monospaceSansSerif">  <span tts:color="yellow">Yellow Monospace</span></p>

<regionxml:id="r1">  <style tts:color="yellow"/>  <style tts:fontFamily="monospaceSerif"/></region>...<pregion="r1">Yellow Monospace</p>

8.4.3 Style Resolution Value Categories

During style resolution, layout, and presentation processing,three categories of style property values are distinguished asfollows:

• specified values

• computed values

• used values

• actual values

8.4.4 Style Resolution Processing

The process of style resolution is defined herein as the procedure(and results thereof) for resolving (determining) the computed valuesof all style properties that apply to content and layout elements:

• 8.4.4.1 Conceptual Definitions

• 8.4.4.2 Specified Style Set Processing

• 8.4.4.3 Computed Style Set Processing

• 8.4.4.4 Style Resolution Process

The process described here forms an integral sub-process of9.3 Region Layout and Presentation.

9.1.1 layout

Thelayout element is a container element used to grouplayout matter, including metadata that applies to layout matter.

Thelayout element accepts as its children zero or moreelements in theMetadata.class element group, followed byzero or moreregion elements.

<layoutxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content:Metadata.class*,region*</layout>

To the extent that time semantics apply to the content of thelayout element, the implied time interval of this element isdefined to be coterminous with theRoot Temporal Extent.

9.1.2 region

Theregion element is used to define a rectangular space or area into which content isto be flowed for the purpose of presentation.

In addition, and in accordance with8.4.2.2 Region Style Inheritance, theregion element may be used to specify inheritable style properties to beinherited by content that is flowed into it.

Theregion element accepts as its children zero or moreelements in theMetadata.class element group,followed by zero or moreelements in theAnimation.class element group,followed byzero or morestyle elements.

Any metadata specified by children in theMetadata.classelement group applies semantically to theregion element and its descendants as a whole.Any animation elements specified by children in theAnimation.classelement group apply semantically to theregion element.Anystyle child element must be considered a local styledefinition that applies only to the containingregionelement, i.e., does not apply for resolving referential styling (but does apply for regionstyle inheritance).

<regionbegin =<timeExpression>dur =<timeExpression>end =<timeExpression>style = IDREFStimeContainer = (par|seq)ttm:role = stringxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*,Animation.class*,style*</region>

Ifbegin and (or)end attributes are specified on aregion element, then they specify the beginning and (or) ending pointsof a time interval during which the region is eligible for activation and withrespect to which animation child elements of the region are timed.If specified, these begin and end points are relative to the timeinterval of the nearest ancestor element associated with a timeinterval, irregardless of whether that interval is explicit or implied.

The nearest ancestor element of aregion element that is associatedwith a time interval is thelayout element.

If adur attribute is specified on theregion element, then itspecifies the simple duration of the region.

For the purpose of determining the semantics of presentation processing, aregion that is temporally inactive must not produce any visible marks whenpresented on a visual medium.

If notimeContainer attribute is specified onaregion element, then it must be interpreted as havingparallel time containment semantics.

If attm:role attribute isspecified on aregion element, then it must adhere to thevalue syntax defined bySyntax Representation – ttm:role, and where the roles identifiedby this attribute express the semantic roles of the regionindependently from the semantic roles of any content targeted to(associated with) the region.

9.2.1 region

Theregion attribute is used to reference aregionelement which defines a space or area into which aContent element is intended to be flowed.

If specified, the value of aregion attribute mustadhere to theIDREF data type defined by[XML Schema Part 2],§ 3.3.9, and, furthermore, this IDREF must reference aregion elementwhich has alayout element as an ancestor.

Theregion attribute may be specified by an instance of the followingelement types:

• body

• div

• p

• span

9.3.1 Default Region

If aDocument Instance does not specify aregion element,then adefault region is implied with the following characteristics:

• the identity of the default region is considered to be anonymous;

• the extent of the default region is the same as the extent of theRoot Container Region;

• the temporal interval of the default region is the same as the interval defined by theRoot Temporal Extent;

Furthermore, if noregion element isspecified, then theregion attribute mustnot be specified on anyContent element in theDocument Instance.

If a default region is implied for a givenDocument Instance, thenthebody elementis implicitly targeted to (associated with) the default region.

When implying a default region, theDocument Instance is to betreated as if aregion element and itsparentlayoutelement were specified in aheadelement, and a matchingregion attribute werespecified on thebody elementas shown in the following example:

<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml">  <head><layout>      <region xml:id="anonymous"/>    </layout>  </head>  <bodyregion="anonymous"/></tt>

9.3.2 Anonymous Span Construction

For the purposes of performing presentation processing, anonymous spans are createdaccording to the following[construct anonymous spans] procedure:

[construct anonymous spans]

1. for each significant text node in aContent element,synthesize an anonymous span to enclose the text node, substitutingthe new anonymous span for the original text node child in its siblingand parent hierarchy;

2. for each contiguous sequence of anonymous spans, replace thesequence with a single anonymous span which contains a sequence oftext nodes representing the individual text node children of theoriginal sequence of anonymous spans;

3. for each span element whose child is a single anonymous span,replace the anonymous span with its sequence of child textnodes;

9.3.3 Intermediate Synchronic Document Construction

For the purposes of performing presentation processing, the active timeduration of aDocument Instance is divided into a sequence of time coordinates where ateach time coordinate, some element becomes temporally active or inactive,then, at each such time coordinate, aDocument Instance is mapped from its original, sourceform,DOC_source , to an intermediatesynchronic document form,DOC_inter , according to the[construct intermediate document] procedure:

[construct intermediate document]

1. for each temporally active regionR, replicate thesub-tree ofDOC_sourceheaded by thebody element;

2. evaluating this sub-tree in a postorder traversal, prune elements if any of the following conditions is true:

   1. they are neitherContent norAnimation elements; or

   2. they are temporally inactive; or

   3. they are empty and neitherAnimation elements norbr elements; or

   4. they areContent elements and aren't associated with regionR according to the[associate region] procedure.

3. if the pruned sub-tree is non-empty, then reparent it to theRelement;

4. finally, after completing the above steps, prune the originalbodyelement from the intermediate document, then prune allregion,begin,end, anddur attributes, which are nolonger semantically relevant;

Note:

In this section, the termprune, when used in reference toan element, means that the element is to be removed from its parent's children,which, in turn, implies that the descendants of the pruned element will no longerbe descendants of the element's parent. Whenprune is used inreference to an attribute, it means that attribute is to be removed from itsassociated (owning) element node.

[associate region]

AContent element is associated with a region accordingto the following ordered rules, where the first rule satisfiedis used and remaining rules are skipped:

1. if the element specifies aregion attribute,then the element is associated with the region referenced by thatattribute;

2. if some ancestor of that element specifies aregion attribute,then the element is associated with the region referenced by the mostimmediate ancestor that specifies this attribute;

3. if the element contains a descendant element thatspecifies aregion attribute,then the element is associated with the region referenced by thatattribute;

4. if a default region was implied (due to the absence of anyregion element),then the element is associated with the default region;

5. the element is not associated with any region.

The result of performing the processing described above will be a sequence ofN intermediate synchronicDocument Instances,DOC_inter0 …DOC_interN−1.

9.3.4 Synchronic Flow Processing

Subsequent to performing a temporal (synchronic) slice and subsequentremapping of regionally selected content hierarchy, the resulting intermediatesynchronic document is subjected to a flow transformation step that produces a rooted flow object tree represented as an XSL FO document instance as defined by[XSL 1.1],and semantically extended by TTML specific style properties that have no XSLFO counterpart.

Each intermediate synchronic document produced by9.3.3 Intermediate Synchronic Document Construction is mapped to an XSL FO document instance,F, as follows:

1. perform the[construct anonymous spans] procedure;

2. resolve styles according to8.4.4.4 Style Resolution Process;

3. map thett element to anfo:root element, populatedinitially with anfo:layout-master-set element that contains a validfo:simple-page-master that, in turn, contains anfo:region-body child, where the extent of theRoot Container Region expressed on thett element is mapped topage-width andpage-height attributes on thefo:simple-page-masterelement;

4. map thelayout element to anfo:page-sequence element and achildfo:flow element that reference the page master and page regiondefined by the simple page master produced above;

5. map each non-emptyregion element to anfo:block-containerelement with anabsolute-position attribute with valueabsolute, withtop,left,bottom, andrightattributes that express a rectangle equivalent to the region's origin, extent (including padding), and with aline-stacking-strategy attribute with valueline-height;

   Note:

   The region's extent corresponds with the allocation rectangle of the block area generated by thefo:block-container.

6. for eachbody,div, andp element that is notassociated with atts:display style property with the valuenone, map the element to a distinctfo:block element,populating the style properties offo:block by using the computedstyle set associated with each original TTMLContent element;

7. for the resultingfo:block formatting objectproduced in the previous step that corresponds to thebodyelement, perform the following ordered sub-steps:

   1. if thedisplay-align style property of thisfo:blockhas the valuecenter orafter,then synthesize and insert as the first child of thisfo:blockan emptyfo:block with the following attributes:space-after.optimum,space-after.maximum, andspace-after.conditionality, where the value of the formertwo attributes is the height or width of the containingfo:block-container element, whichever of these is designatedas the block progression dimension, and where the value of the last isretain;

   2. if thedisplay-align style property of thisfo:blockhas the valuecenter orbefore,then synthesize and insert as the last child of thisfo:blockan emptyfo:block with the following attributes:space-after.optimum,space-after.maximum, andspace-after.conditionality, where the value of the formertwo attributes is the height or width of the containingfo:block-container element, whichever of these is designatedas the block progression dimension, and where the value of the last isretain;

8. for eachspan element that is notassociated with atts:display style property with the valuenone and for each anonymousspan that is a child of ap orspan element,map the element orsequence of character items to a distinctfo:inline element,populating the style properties offo:inline by using the computedstyle set associated with each original TTMLContent elementor anonymous span;

9. for eachbr element that is notassociated with atts:display style property with the valuenone, map the element toa distinctfo:character element having the followingproperties:

   • character="
"

   • suppress-at-line-break="retain"

10. for each TTML style property attribute in some computedstyle set thathas no counterpart in[XSL 1.1], map that attribute directly throughto the relevant formatting object produced by the input TTMLContent element towhich the style property applies;

11. optionally, synthesize a uniqueid attribute on each resultingformatting object element that relates that element to the input element thatresulted in that formatting object element;

For each resulting document instance F, if processing requires presentation on a visual medium, then apply formatting and rendering semantics consistent with that prescribed by[XSL 1.1].

9.3.5 Elaborated Example (Informative)

An example of the processing steps described above is elaborated below, starting withExample – Sample Source Document.

<tt tts:extent="640px 480px" xml:lang="en"  xmlns="http://www.w3.org/ns/ttml"  xmlns:tts="http://www.w3.org/ns/ttml#styling">  <head>    <layout>      <region xml:id="r1">        <style tts:origin="10px 100px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="red"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>      </region>      <region xml:id="r2">        <style tts:origin="10px 300px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="yellow"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>      </region>    </layout>  </head>  <body xml:id="b1">    <div xml:id="d1" begin="0s" dur="2s">      <p xml:id="p1" region="r1">Text 1</p>      <p xml:id="p2" region="r2">Text 2</p>    </div>    <div xml:id="d2" begin="1s" dur="2s">      <p xml:id="p3" region="r2">Text 3</p>      <p xml:id="p4" region="r1">Text 4</p>    </div>  </body></tt>

In the above document, the content hierarchy consists of two divisions, eachcontaining two paragraphs. This content is targeted (associated with) one of twonon-overlapping regions that are styled identically except for their positionand their foreground colors, the latter of which is inherited by and applies tothe (and, in this case, anonymous) spans reparented into the regions.

The following, first intermediate document shows the synchronic state for timeinterval [0,1), during which time only divisiond1 is temporally active,and where paragraphsp1 andp2 (and their ancestors)are associated with regionsr1 andr2, respectively.

<tt tts:extent="640px 480px" xml:lang="en"  xmlns="http://www.w3.org/ns/ttml"  xmlns:tts="http://www.w3.org/ns/ttml#styling">  <head>    <layout>      <region xml:id="r1">        <style tts:origin="10px 100px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="red"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>        <body xml:id="b1-1">          <div xml:id="d1-1">            <p xml:id="p1">Text 1</p>          </div>        </body>      </region>      <region xml:id="r2">        <style tts:origin="10px 300px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="yellow"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>        <body xml:id="b1-2">          <div xml:id="d1-2">            <p xml:id="p2">Text 2</p>          </div>        </body>      </region>    </layout>  </head></tt>

An XSL FO document instance that would yield rendering consistent with TTML, and which may be produced by performing flow processing upon the first intermediate document is illustrated below.

<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">  <fo:layout-master-set>    <fo:simple-page-master master-name="m1"      page-width="640px" page-height="480px">      <fo:region-body/>    </fo:simple-page-master>  </fo:layout-master-set>  <fo:page-sequence master-reference="m1">    <fo:flow flow-name="xsl-region-body">      <!-- region (r1) -->      <fo:block-container absolute-position="absolute"        left="10px" top="100px" width="620px" height="96px"        background-color="black" display-align="center">        <!-- body (b1) -->        <fo:block>          <!-- body's space (before) filler -->          <fo:block            space-after.optimum="96px"            space-after.maximum="96px"            space-after.conditionality="retain"/>          <!-- div (d1) -->          <fo:block>            <!-- p (p1) -->            <fo:block text-align="center">              <fo:inline font-size="40px" font-weight="bold"              color="red">Text 1</fo:inline>            </fo:block>          </fo:block>          <!-- body's space (after) filler -->          <fo:block            space-after.optimum="96px"            space-after.maximum="96px"            space-after.conditionality="retain"/>        </fo:block>      </fo:block-container>      <!-- region (r2) -->      <fo:block-container absolute-position="absolute"        left="10px" top="300px" width="620px" height="96px"        background-color="black" display-align="center">        <!-- body (b1) -->        <fo:block>          <!-- body's space (before) filler -->          <fo:block            space-after.optimum="96px"            space-after.maximum="96px"            space-after.conditionality="retain"/>          <!-- div (d1) -->          <fo:block>            <!-- p (p2) -->            <fo:block text-align="center">              <fo:inline font-size="40px" font-weight="bold"              color="yellow">Text 2</fo:inline>            </fo:block>          </fo:block>          <!-- body's space (after) filler -->          <fo:block            space-after.optimum="96px"            space-after.maximum="96px"            space-after.conditionality="retain"/>        </fo:block>      </fo:block-container>    </fo:flow>  </fo:page-sequence></fo:root>

The following, second intermediate document shows the synchronic state fortime interval [1,2), during which time both divisionsd1 andd2 are temporally active, and where paragraphsp1 andp4 (and their ancestors) are associated with regionr1and paragraphsp2 andp3 (and their ancestors) areassociated with regionr2.

<tt tts:extent="640px 480px" xml:lang="en"  xmlns="http://www.w3.org/ns/ttml"  xmlns:tts="http://www.w3.org/ns/ttml#styling">  <head>    <layout>      <region xml:id="r1">        <style tts:origin="10px 100px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="red"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>        <body xml:id="b1-1">          <div xml:id="d1-1">            <p xml:id="p1">Text 1</p>          </div>          <div xml:id="d2-1">            <p xml:id="p4">Text 4</p>          </div>        </body>      </region>      <region xml:id="r2">        <style tts:origin="10px 300px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="yellow"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>        <body xml:id="b1-2">          <div xml:id="d1-2">            <p xml:id="p2">Text 2</p>          </div>          <div xml:id="d2-2">            <p xml:id="p3">Text 3</p>          </div>        </body>      </region>    </layout>  </head></tt>

The following, third intermediate document shows the synchronic state for timeinterval [2,3), during which time only divisiond2 is temporally active,and where paragraphsp4 andp3 (and their ancestors)are associated with regionsr1 andr2, respectively.

<tt tts:extent="640px 480px" xml:lang="en"  xmlns="http://www.w3.org/ns/ttml"  xmlns:tts="http://www.w3.org/ns/ttml#styling">  <head>    <layout>      <region xml:id="r1">        <style tts:origin="10px 100px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="red"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>        <body xml:id="b1-1">          <div xml:id="d2-1">            <p xml:id="p4">Text 4</p>          </div>        </body>      </region>      <region xml:id="r2">        <style tts:origin="10px 300px"/>        <style tts:extent="620px 96px"/>        <style tts:fontSize="40px"/>        <style tts:fontWeight="bold"/>        <style tts:backgroundColor="black"/>        <style tts:color="yellow"/>        <style tts:textAlign="center"/>        <style tts:displayAlign="center"/>        <body xml:id="b1-2">          <div xml:id="d2-2">            <p xml:id="p3">Text 3</p>          </div>        </body>      </region>    </layout>  </head></tt>

10.2.1 begin

Thebegin attribute is used to specify the beginpoint of a temporal interval associated with a timed element. Ifspecified, the value of abegin attribute must adhere toa <timeExpression> specification as defined by10.3.1 <timeExpression>.

The begin point of a temporal interval is included in theinterval; i.e., the interval is left-wise closed.

The semantics of thebegin attribute are those definedby[SMIL 2.1], § 10.4.1,while taking into account any overriding semantics defined by this specification.

10.2.2 end

Theend attribute is used to specify the ending pointof a temporal interval associated with a timed element. Ifspecified, the value of anend attribute must adhere to a<timeExpression> specification as defined by10.3.1 <timeExpression>.

The ending point of a temporal interval is not included in theinterval; i.e., the interval is right-wise open.

The presentation effects of a non-empty activetemporal interval include the frame immediately prior to the frame(or tick) equal to or immediately following the time specified by the endingpoint, but do not extend into this latter frame (or tick).

The semantics of theend attribute are those definedby[SMIL 2.1], § 10.4.1,while taking into account any overriding semantics defined by this specification.

10.2.3 dur

Thedur attribute is used to specify the duration of atemporal interval associated with a timed element. If specified,the value of adur attribute must adhere to a<timeExpression> specification as defined by10.3.1 <timeExpression>.

When aDocument Instance specifies the use of thesmpte time base anddiscontinuous markermode, a (well-formed)dur attribute must not be specified on anyelement.

The semantics of thedur attribute are those definedby[SMIL 2.1], § 10.4.1,while taking into account any overriding semantics defined by this specification. In a deliberate divergence from[SMIL 2.1], § 10.4.1, the value of thedur attribute is permitted to be zero (0).

10.2.4 timeContainer

ThetimeContainer attribute is used to specify a local temporalcontext by means of which timed child elements are temporally situated.

If specified, the value of atimeContainer attribute must be oneof the following:

• par

• seq

If the time container semantics of an element instance ispar,then the temporal intervals of child elements are considered to apply inparallel, i.e., simultaneously in time. Furthermore, the specification ofthe time interval of each child element is considered to be relative to the temporalinterval of the container element instance. For the purpose of determining the[SMIL 2.1]endsync semantics of apartime container, a default value ofall applies.

If the time container semantics of an element instance isseq,then the temporal intervals of child elements are considered to apply insequence, i.e., sequentially in time. Furthermore, the specification ofthe time interval of each child element is considered to be relative to the temporalinterval of its sibling elements, unless it is the first child element, in which caseit is considered to be relative to the temporal interval of the containerelement instance.

Each time container is considered to constitute an independent time base, i.e.,time coordinate system.

If atimeContainer attribute is not specified on an element thathas time container semantics, thenpar time container semantics must apply.

Time container semantics applies only to the following element types:

• body

• div

• p

• region

• span

The semantics of parallel and sequential timecontainment are those defined by[SMIL 2.1], § 10.4.2,while taking into account any overriding semantics defined by this specification.

10.3.1 <timeExpression>

A <timeExpression> is used to specify a coordinate withinsome time base, where the applicable time base is determined by thettp:timeBase parameter, and where the semantics definedbyN Time Expression Semantics apply.

<timeExpression>  : clock-time  | offset-timeclock-time  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?offset-time  : time-count fraction? metrichours  :<digit><digit>  |<digit><digit><digit>+minutes | seconds  :<digit><digit>frames  :<digit><digit>  |<digit><digit><digit>+sub-frames  :<digit>+fraction  : "."<digit>+time-count  :<digit>+metric  : "h"                 // hours  | "m"                 // minutes  | "s"                 // seconds  | "ms"                // milliseconds  | "f"                 // frames  | "t"                 // ticks

If a <timeExpression> is expressed in terms of aclock-time, then leading zeroes are used when expressing hours,minutes, seconds, and frames less than 10. Minutes are constrained to[0…59], while seconds (including any fractional part) are constrained to the closedinterval [0,60], where the value 60 applies only to leap seconds. Except whenttp:timeBase isclock andttp:clockMode islocal orutc, use of the special value of 60 seconds to denote a leap second is undefined and should not be used.

If a <timeExpression> is expressed in terms of aclock-time and aframes term is specified,then the value of this term must be constrained to the interval[0…F-1], whereF is the frame ratedetermined by thettp:frameRate parameter as definedby6.2.4 ttp:frameRate.It is considered an error if aframes term orf (frames) metric is specified when theclock time base applies.

If a <timeExpression> is expressed in terms of aclock-time and asub-frames term isspecified, then the value of this term must be constrained to theinterval [0…S-1], whereS is thesub-frame rate determined by thettp:subFrameRate parameter as defined by6.2.9 ttp:subFrameRate.It is considered an error if asub-frames term is specifiedwhen theclock time base applies.

If the governing time base issmpte, then (1) theoffset-time form is not defined and should not be used, and (2) thefraction seconds component in aclock-time form is not defined and should not be used.

11.1.1 set

Theset element is used as a child element of aContent element or aregion elementin order to express a discrete change of some style parameter valuethat applies over some time interval.

Theset element accepts as its children zero or moreelements in theMetadata.class element group.

<setbegin =<timeExpression>dur =<timeExpression>end =<timeExpression>xml:id = IDxml:lang = stringxml:space = (default|preserve)  {a single attribute in TT Style namespace}  {any attribute not in default or any TT namespace}>Content:Metadata.class*</set>

An example of using theset element to animate contentstyling is illustrated below:

...<p dur="5s" tts:color="yellow"><set begin="1s" dur="1s" tts:color="red"/><set begin="2s" dur="1s" tts:color="green"/><set begin="3s" dur="1s" tts:color="red"/>Text with Flashing Colors!</p>...

An example of using theset element to animate regionstyling is illustrated below:

<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"    xmlns:ttp="http://www.w3.org/ns/ttml#parameter"    xmlns:tts="http://www.w3.org/ns/ttml#styling"    ttp:cellResolution="40 16">    <head>      <layout><region xml:id="r1" timeContainer="seq"><set dur="10s" tts:origin=" 8c 14c"/><set dur="2s"  tts:origin=" 2c  2c"/><set dur="3s"  tts:origin=" 8c 14c"/><set dur="2s"  tts:origin="14c  4c"/><set dur="10s" tts:origin=" 8c 14c"/>  <style tts:extent="24c 2c"/></region>      </layout>    </head>    <body region="r1">...</body></tt>

12.1.1 metadata

Themetadata element functions as a generic container for metadatainformation.

Metadata information may be expressed with ametadata element by specifying(1) one or more metadata attributes on themetadata element,(2) one or more metadata child elements in themetadata element, or(3) a combination of metadata attributes and metadata child elements. Both typesof metadata information are referred to in this document asmetadataitems.

<metadataxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute in TT Metadata namespace}  {any attribute not in default or any TT namespace}>Content: ({any element in TT Metadata namespace}|{any element not in any TT namespace})*</metadata>

The use of document metadata is illustrated by the following example.

...<head>  <metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata">    <ttm:title>Document Metadata Example</ttm:title>    <ttm:desc>This document employs document metadata.</ttm:desc>  </metadata></head>...

The use of element metadata is illustrated by the following example.

...<div>  <metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata">    <ttm:title>Chapter 6 – Sherlock Holmes Gives a Demonstration</ttm:title>    <ttm:desc>Holmes shows Watson how the murderer entered the window.</ttm:desc>  </metadata></div>...

The use of metadata attribute items is illustrated by the following example.

...<div xmlns:ext="http://example.org/ttml#metadata">  <metadata ext:ednote="remove this division prior to publishing"/></div>...

The use of foreign element metadata is illustrated by the following example.

...<metadata  xmlns:dc="http://purl.org/dc/elements/1.1/"  xmlns:dcterms="http://purl.org/dc/terms/"  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">  <dc:title>Foreign Element Metadata Example</dc:title>  <dc:description>Express metadata using elements in foreign namespace.</dc:description>  <dc:format xsi:type="dcterms:IMT">application/ttml+xml</dc:format></metadata>...

12.1.2 ttm:title

Thettm:title element is used to express a human-readable title ofa specific element instance.

<ttm:titlexml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content: #PCDATA</ttm:title>

Examples of thettm:title element are shown above inExample Fragment – Document Metadata andExample Fragment – Element Metadata.

12.1.3 ttm:desc

Thettm:desc element is used to express a human-readable description ofa specific element instance.

<ttm:descxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content: #PCDATA</ttm:desc>

Examples of thettm:desc element are shown above inExample Fragment – Document Metadata andExample Fragment – Element Metadata.

12.1.4 ttm:copyright

Thettm:copyright element is used to express a human-readable copyright thatapplies to some scoping level.

A copyright statement that applies to a document as a whole should appear as achild of thehead element.

<ttm:copyrightxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content: #PCDATA</ttm:copyright>

12.1.5 ttm:agent

Thettm:agent element is used to define an agent for the purpose of associatingcontent information with an agent who is involved in the production or expression of that content.

Thettm:agent element accepts as its children zero or morettm:name elements followed byzero or onettm:actor element.

At least onettm:name element child should be specified that expresses a name for theagent, whether it be the name of a person, character, group, or organization.

<ttm:agenttype = (person|character|group|organization|other)xml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content:ttm:name*,ttm:actor?</ttm:agent>

Atype attribute must be specified on eachttm:agent element, and,if specified, must have one of the following values:

• person

• character

• group

• organization

• other

If the value of thetype attribute ischaracter, then thettm:agent element instance should specify attm:actor child thatspecifies the agent that plays the role of the actor.

Attm:agent metadata item is considered to be significant onlywhen specified as a child of thehead element or as a child of ametadata element child of thehead element.

The use of agent metadata is illustrated by the following example.

<tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml" xmlns:ttm="http://www.w3.org/ns/ttml#metadata">  <head><ttm:agent xml:id="connery" type="person">      <ttm:name type="family">Connery</ttm:name>      <ttm:name type="given">Thomas Sean</ttm:name>      <ttm:name type="alias">Sean</ttm:name>      <ttm:name type="full">Sir Thomas Sean Connery</ttm:name></ttm:agent><ttm:agent xml:id="bond" type="character">      <ttm:name type="family">Bond</ttm:name>      <ttm:name type="given">James</ttm:name>      <ttm:name type="alias">007</ttm:name>      <ttm:actor agent="connery"/></ttm:agent>  </head>  <body>    <div>      ...        <pttm:agent="bond">I travel, a sort of licensed troubleshooter.</p>      ...      </div>  </body></tt>

12.1.6 ttm:name

Thettm:name element is used to specify a name of a person, character,group, or organization.

<ttm:nametype = (full|family|given|alias|other)xml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content: #PCDATA</ttm:name>

Atype attribute must be specified on eachttm:name element, and,if specified, must have one of the following values:

• full

• family

• given

• alias

• other

The relationship between the type of a name and the syntactic expression of the nameis not defined by this specification.

Two examples of thettm:name element are shown above inExample Fragment – Agent Metadata.

12.1.7 ttm:actor

Thettm:actor element is used to link the definition of a (role-based) characteragent with another agent that portrays the character.

<ttm:actoragent = IDREFxml:id = IDxml:lang = stringxml:space = (default|preserve)  {any attribute not in default or any TT namespace}>Content: EMPTY</ttm:actor>

Theagent attribute of attm:actor element mustreference asignificantttm:agent element that denotes the agentacting the part of a character.

Anttm:actor element referencing its parentttm:agent element should be considered an error.

An example of thettm:actor element is shown above inExample Fragment – Agent Metadata.

Note:

Only certain metadata item attributes may be used withContent elements. Seethe definitions ofContent elements to determine permissible usage.

12.2.1 ttm:agent

Thettm:agent attribute takes anIDREFSvalue, and is used with certainContent elements to designate theagents that perform or areinvolved in the performance of the content.

If specified, attm:agent attribute must referencesignificantttm:agent element instances.

The same IDREF,ID, should not appear more than once in the value of attm:agent attribute.

An example of thettm:agent attribute is shown above inExample Fragment – Agent Metadata.

12.2.2 ttm:role

Thettm:role attribute may be used by a content authorto expressthe roles, functions, or characteristicsof someContent element that is so labeled.

If specified, the value of this attribute must adhere to the followingsyntax, wherethe syntactic elementS must adhere to production[3]S as defined by[XML 1.0] §2.3:

ttm:role  role (S role )*role  : "action"  | "caption"  | "description"  | "dialog"  | "expletive"  | "kinesic"  | "lyrics"  | "music"  | "narration"  | "quality"  | "sound"  | "source"  | "suppressed"  | "reproduction"  | "thought"  | "title"  | "transcription"  | extension-roleextension-role  : "x-" token-char+token-char  : { XML NameChar }    // XML 1.1 Production [4a]

The samerole token,R, should not appear more than once in the value of attm:role attribute.

feature-designation  : feature-namespace designationfeature-namespace  :TT Feature Namespace                    // http://www.w3.org/ns/ttml/feature/designation  : "#" token-char+token-char  : { XML NameChar }                        // XML 1.1 Production [4a]

D.1.1 #animation

A TTML transformation processor supports the#animationfeature if it recognizes and is capable of transforming the followingvocabulary defined by11 Animation:

• set