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Network Working Group                                     H. SchulzrinneRequest for Comments: 4480                                   Columbia U.Category: Standards Track                                     V. Gurbani                                                                  Lucent                                                              P. Kyzivat                                                            J. Rosenberg                                                                   Cisco                                                               July 2006RPID: Rich Presence Extensions to thePresence Information Data Format (PIDF)Status of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).Abstract   The Presence Information Data Format (PIDF) defines a basic format   for representing presence information for a presentity.  This format   defines a textual note, an indication of availability (open or   closed) and a Uniform Resource Identifier (URI) for communication.   The Rich Presence Information Data format (RPID) described here is an   extension that adds optional elements to the Presence Information   Data Format (PIDF).  These extensions provide additional information   about the presentity and its contacts.  The information is designed   so that much of it can be derived automatically, e.g., from calendar   files or user activity.   This extension includes information about what the person is doing, a   grouping identifier for a tuple, when a service or device was last   used, the type of place a person is in, what media communications   might remain private, the relationship of a service tuple to another   presentity, the person's mood, the time zone it is located in, the   type of service it offers, an icon reflecting the presentity's   status, and the overall role of the presentity.   These extensions include presence information for persons, services   (tuples), and devices.Schulzrinne, et al.         Standards Track                     [Page 1]

RFC 4480                          RIPD                         July 2006Table of Contents1. Introduction ....................................................22. Terminology and Conventions .....................................43. RPID Elements ...................................................43.1. Overview ...................................................43.2. Activities Element .........................................73.3. Class Element .............................................103.4. Device Identifier .........................................103.5. Mood Element ..............................................103.6. Place-is Element ..........................................123.7. Place-type Element ........................................133.8. Privacy Element ...........................................143.9. Relationship Element ......................................153.10. Service Class ............................................153.11. Sphere Element ...........................................163.12. Status-Icon Element ......................................163.13. Time Offset ..............................................173.14. User-Input Element .......................................174. Example ........................................................185. XML Schema Definitions .........................................205.1. urn:ietf:params:xml:ns:pidf:rpid ..........................206. Extending RPID .................................................307. IANA Considerations ............................................317.1. URN Sub-Namespace Registration for ........................31           'urn:ietf:params:xml:ns:pidf:rpid'7.2. Schema Registration for Schema ............................32           'urn:ietf:params:xml:ns:pidf:status:rpid'8. Internationalization Considerations ............................329. Security Considerations ........................................3210. References ....................................................3310.1. Normative References .....................................3310.2. Informative References ...................................34Appendix A.  Acknowledgements .....................................351.  Introduction   The Presence Information Data Format (PIDF) definition [8] describes   a basic presence information data format, encoded as an Extensible   Markup Language (XML) [9] (SCHEMA-1 [10]) (SCHEMA-2 [11]), for   exchanging presence information in systems compliant with the common   model for presence and instant messaging [5].  It consists of a   <presence> root element, zero or more <tuple> elements carrying   presence information including a Uniform Resource Identifier (URI)   for communication, zero or more <note> elements, and zero or more   extension elements from other name spaces.  Each tuple defines a   basic status of either "open" or "closed".Schulzrinne, et al.         Standards Track                     [Page 2]

RFC 4480                          RIPD                         July 2006   However, it is frequently useful to convey additional information   about a user that needs to be interpreted by an automata, and is   therefore not appropriate to be placed in the <note> element of the   PIDF document, which is typically intended for the human observer.   Therefore, this specification defines extensions to the PIDF document   format for conveying richer presence information.  Generally, the   extensions have been chosen to provide features common in existing   presence systems at the time of writing, in addition to elements that   could readily be derived automatically from existing sources of   presence, such as calendaring systems or communication devices, or   sources describing the user's current physical environment.   The presence data model [16] defines the concepts of service, device,   and person as the data elements that are used to model the state of a   presentity.  (The term "presentity" is defined inRFC 2778 [5] and   abbreviates presence entity.  A presentity provides presence   information to a presence service.)  Services are encoded using the   <tuple> element, defined in PIDF; devices and persons are represented   by the <device> and <person> XML elements, respectively, defined in   the data model [16].  However, neither PIDF nor the data model   defines presence attributes beyond the <basic> status element.   This specification defines additional presence attributes to describe   person, service, and device data elements, summarized as "Rich   Presence Information Data format for presence" (RPID).  These   attributes are specified by XML elements that extend the PIDF <tuple>   element and the <device> and <person> elements defined in the data   model.   This extension has two main goals:   1.  Provide rich presence information that is at least as powerful as       common commercial presence systems.  Such feature-parity       simplifies transition to systems complying with the Common       Profile for Instant Messaging (CPIM) [14], both in terms of user       acceptance and protocol conversion.   2.  Maintain backward-compatibility with PIDF, so that PIDF-only       watchers and gateways can continue to function properly,       naturally without access to the functionality described here.   We make no assumptions as to how the information in the RPID elements   is generated.  Experience has shown that users are not always   diligent about updating their presence status.  Thus, we want to make   it as easy as possible to derive RPID information from other   information sources, such as personal calendars, the status of   communication devices such as telephones, typing activity, andSchulzrinne, et al.         Standards Track                     [Page 3]

RFC 4480                          RIPD                         July 2006   physical presence detectors as commonly found in energy-management   systems.   Many of the elements correspond to data commonly found in personal   calendars.  Thus, we attempted to align some of the extensions with   the usage found in calendar formats such as iCal [13].   The information in a presence document can be generated by a single   entity or can be composed from information published by multiple   entities.   Note that PIDF documents and this extension can be used in two   different contexts, namely, by the presentity to publish its presence   status and by the presence server to notify some set of watchers.   The presence server MAY compose, translate, or filter the published   presence state before delivering customized presence information to   the watcher.  For example, it may merge presence information from   multiple presence user agents, remove whole elements, translate   values in elements, or remove information from elements.  Mechanisms   that filter calls and other communications to the presentity can   subscribe to this presence information just like a regular watcher   and in turn generate automated rules, such as scripts [15], that   govern the actual communications behavior of the presentity.  Details   are described in the data model document.   Since RPID is a PIDF XML document, it also uses the content type   application/pidf+xml.2.  Terminology and Conventions   This memo makes use of the vocabulary defined in the IMPP model   document [5].  Terms such as CLOSED, INSTANT MESSAGE, OPEN, PRESENCE   SERVICE, PRESENTITY, WATCHER, and WATCHER USER AGENT in the memo are   used in the same meaning as defined therein.   The key words MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT,   RECOMMENDED, MAY, and OPTIONAL in this document are to be interpreted   as described inBCP 14,RFC 2119 [1].3.  RPID Elements3.1.  Overview   Some of the RPID elements describe services, some devices, and some   the person.  As such, they either extend <tuple>, <device>, or   <person>, respectively.  Below, we summarize the RPID elements.  The   next sections will then provide more detailed descriptions.Schulzrinne, et al.         Standards Track                     [Page 4]

RFC 4480                          RIPD                         July 2006   activities:  The <activities> status element enumerates what the      person is doing.   class:  An identifier that groups similar person elements, devices,      or services.   deviceID:  A device identifier in a tuple references a <device>      element, indicating that this device contributes to the service      described by the tuple.   mood:  The <mood> status element indicates the mood of the person.   place-is:  The <place-is> status element reports on the properties of      the place the presentity is currently at, such as the levels of      light and noise.   place-type:  The <place-type> status elements reports the type of      place the person is located in, such as 'classroom' or 'home'.   privacy:  The <privacy> element distinguishes whether the      communication service is likely to be observable by other parties.   relationship:  When a service is likely to reach a user besides the      person associated with the presentity, the relationship indicates      how that user relates to the person.   service-class:  The <service-class> element describes whether the      service is delivered electronically, is a postal or delivery      service, or describes in-person communications.   sphere:  The <sphere> element characterizes the overall current role      of the presentity.   status-icon:  The <status-icon> element depicts the current status of      the person or service.   time-offset:  The <time-offset> status element quantifies the time      zone the person is in, expressed as the number of minutes away      from UTC.   user-input:  The <user-input> element records the user-input or usage      state of the service or device, based on human user input.   The 'From/until?' column in Table 1 indicates by an 'x' that the   element can take 'from' and 'until' attributes.  An 'x' in the   'Note?' column marks elements that can include a <note> element.  The   usage of these elements within the <person>, <tuple>, and <device>   elements is shown in columns 4 through 6.  An 'x' in the respectiveSchulzrinne, et al.         Standards Track                     [Page 5]

RFC 4480                          RIPD                         July 2006   column indicates that the RPID element MAY appear as a child of that   element. +-----------------+------------+------+----------+---------+----------+ | Element         | From/until | Note | <person> | <tuple> | <device> | |                 | ?          | ?    |          |         |          | +-----------------+------------+------+----------+---------+----------+ | <activities>    |      x     |   x  |     x    |         |          | | <class>         |            |      |     x    |    x    |     x    | | <deviceID>      |            |      |          |    x    |          | | <mood>          |      x     |   x  |     x    |         |          | | <place-is>      |      x     |   x  |     x    |         |          | | <place-type>    |      x     |   x  |     x    |         |          | | <privacy>       |      x     |   x  |     x    |    x    |          | | <relationship>  |            |   x  |          |    x    |          | | <service-class> |            |   x  |          |    x    |          | | <sphere>        |      x     |      |     x    |         |          | | <status-icon>   |      x     |      |     x    |    x    |          | | <time-offset>   |      x     |      |     x    |         |          | | <user-input>    |            |      |     x    |    x    |     x    | +-----------------+------------+------+----------+---------+----------+                                  Table 1   In general, it is unlikely that a presentity will publish or announce   all of these elements at the same time.  Rather, these elements were   chosen to give the presentity maximum flexibility in deriving this   information from existing sources, such as calendaring tools, device   activity sensors, or location trackers, as well as to manually   configure this information.  In either case, there is no guarantee   that the information is accurate, as users forget to update calendars   or may not always adjust the presence information manually.   The namespace URIs for these elements defined by this specification   are URNs [2], using the namespace identifier 'ietf' defined by [4]   and extended by [6]:      urn:ietf:params:xml:ns:pidf:rpid   The elements marked with the value 'x' in column 2 of Table 1 MAY be   qualified with the 'from' and 'until' attributes to describe the   absolute time when the element assumed this value and the absolute   time until which this element is expected to be valid.  Note that   there can be multiple elements of the same type, whose time ranges   SHOULD NOT overlap.   Elements MAY contain an 'id' attribute that allows to uniquely   reference the element.Schulzrinne, et al.         Standards Track                     [Page 6]

RFC 4480                          RIPD                         July 2006   Enumerations can be extended by elements from other namespaces, as   described inSection 6.  The <activities>, <mood>, and <place-type>   elements can also take <other> elements containing text, for custom   free-text values specific to an application.   All elements described in this document are optional within PIDF   documents.3.2.  Activities Element   The <activities> element describes what the person is currently   doing, expressed as an enumeration of activity-describing elements.   A person can be engaged in multiple activities at the same time,   e.g., traveling and having a meal.  The <activities> element can be   quite helpful to the watcher in judging how appropriate a   communication attempt is and which means of communications is most   likely to succeed and not annoy the person.  The activity indications   correspond roughly to the category field in calendar entries, such asSection 4.8.1.2 of RFC 2445 [13].   An activities enumeration consists of one or more elements using   elements drawn from the list below, a string enclosed in the <other>   element, or IANA-registered values from other namespaces (Section 7).   If a person publishes an activity of "permanent-absence", it is   likely that all services will report a status of CLOSED.  In general,   services MAY advertise either service status for any activity value.   Activities such as <appointment>, <breakfast>, <dinner>, <holiday>,   <lunch>, <meal>, <meeting>, <performance>, <travel>, or <vacation>   can often be derived from calendar information.   appointment:  The person has a calendar appointment, without      specifying exactly of what type.  This activity is indicated if      more detailed information is not available or the person chooses      not to reveal more information.   away:  The person is physically away from all interactive      communication devices.  This activity element was included since      it can often be derived automatically from security systems,      energy management systems, or entry badge systems.  Although this      activity would typically be associated with a status of CLOSED      across all services, a person may declare himself or herself awaySchulzrinne, et al.         Standards Track                     [Page 7]

RFC 4480                          RIPD                         July 2006      to discourage communication, but indicate that he or she still can      be reached if needed.  However, communication attempts might reach      an answering service, for example.   breakfast:  The person is eating the first meal of the day, usually      eaten in the morning.   busy:  The person is busy, without further details.  Although this      activity would typically be associated with a status of CLOSED      across all services, a person may declare himself or herself busy      to discourage communication, but indicate that he or she still can      be reached if needed.   dinner:  The person is having his or her main meal of the day, eaten      in the evening or at midday.   holiday:  This is a scheduled national or local holiday.   in-transit:  The person is riding in a vehicle, such as a car, but      not steering.  The <place-type> element provides more specific      information about the type of conveyance the person is using.   looking-for-work:  The presentity is looking for (paid) work.   lunch:  The person is eating his or her midday meal.   meal:  The person is scheduled for a meal, without specifying whether      it is breakfast, lunch, or dinner, or some other meal.   meeting:  The person is in an assembly or gathering of people, as for      a business, social, or religious purpose.  A meeting is a sub-      class of an appointment.   on-the-phone:  The person is talking on the telephone.  This activity      is included since it can often be derived automatically.   other:  The person is engaged in an activity with no defined      representation as an <activities> element.  The enclosed string      describes the activity in plain text.   performance:  A performance is a sub-class of an appointment and      includes musical, theatrical, and cinematic performances as well      as lectures.  It is distinguished from a meeting by the fact that      the person may either be lecturing or be in the audience, with a      potentially large number of other people, making interruptions      particularly noticeable.Schulzrinne, et al.         Standards Track                     [Page 8]

RFC 4480                          RIPD                         July 2006   permanent-absence:  The person will not return for the foreseeable      future, e.g., because it is no longer working for the company.      This activity is associated with a status of CLOSED across all      services.   playing:  The person is occupying himself or herself in amusement,      sport, or other recreation.   presentation:  The person is giving a presentation, lecture, or      participating in a formal round-table discussion.   shopping:  The person is visiting stores in search of goods or      services.   sleeping:  This activity category can often be generated      automatically from a calendar, local time information, or      biometric data.   spectator:  The person is observing an event, such as a sports event.   steering:  The person is controlling a vehicle, watercraft, or plane.   travel:  The person is on a business or personal trip, but not      necessarily in-transit.   tv:  The person is watching television.   unknown:  The activity of the person is unknown.  This element is      generally not used together with other activities.   vacation:  A period of time devoted to pleasure, rest, or relaxation.   working:  The presentity is engaged in, typically paid, labor, as      part of a profession or job.   worship:  The presentity is participating in religious rites.   The <activities> element MAY be qualified with the 'from' and 'until'   attributes as described inSection 3.1.   Example:     <activities>       <note>Enjoying the morning paper</note>       <vacation/>       <breakfast/>       <other>reading</other>     </activities>Schulzrinne, et al.         Standards Track                     [Page 9]

RFC 4480                          RIPD                         July 20063.3.  Class Element   The <class> element describes the class of the service, device, or   person.  Multiple elements can have the same class name within a   presence document, but each person, service, or device can only have   one class label.  The naming of classes is left to the presentity.   The presentity can use this information to group similar services,   devices, or person elements or to convey information that the   presence agent can use for filtering or authorization.  This   information is not generally presented to the watcher user interface.   The <class> element MUST NOT be qualified with the 'from' and 'until'   attributes as described inSection 3.1.3.4.  Device Identifier   The <deviceID> element in the <tuple> element references the device   that provides a particular service.  The element is defined   syntactically in the data model [16] schema.  One service can be   provided by multiple devices, so that each service tuple may contain   zero or more <deviceID> elements.  There is no significance in the   order of these elements.   The <deviceID> element MUST NOT be qualified with the 'from' and   'until' attributes as described inSection 3.1.3.5.  Mood Element   The <mood> element describes the mood of the presentity.  The mood   values are enumerated chosen by the presentity.  The mood itself is   provided as the element name of a defined child element of the <mood>   element (e.g., <happy/>); one such child element is REQUIRED.  The   user MAY also specify a natural-language description of, or reason   for, the mood in the <note> child of the <mood> element, which is   OPTIONAL.  (This definition follows the Jabber Extension JEP-107.)   It is RECOMMENDED that an implementation support the mood values   proposed in Jabber Extension JEP-0107, which in turn are a superset   of the Wireless Village [18] mood values and the values enumerated in   the Affective Knowledge Representation that has been defined by   Lisetti [17]:   A mood enumeration consists of one or more elements using elements   drawn from the list below, a string enclosed in the <other> element,   or IANA-registered values from other namespaces (Section 7).   The <mood> element MAY be qualified with the 'from' and 'until'   attributes as described inSection 3.1.Schulzrinne, et al.         Standards Track                    [Page 10]

RFC 4480                          RIPD                         July 2006   o  afraid   o  amazed   o  angry   o  annoyed   o  anxious   o  ashamed   o  bored   o  brave   o  calm   o  cold   o  confused   o  contented   o  cranky   o  curious   o  depressed   o  disappointed   o  disgusted   o  distracted   o  embarrassed   o  excited   o  flirtatious   o  frustrated   o  grumpy   o  guilty   o  happy   o  hot   o  humbled   o  humiliated   o  hungry   o  hurt   o  impressed   o  in_awe   o  in_love   o  indignant   o  interested   o  invincible   o  jealous   o  lonely   o  mean   o  moody   o  nervous   o  neutral   o  offended   o  other   o  playful   o  proud   o  relieved   o  remorsefulSchulzrinne, et al.         Standards Track                    [Page 11]

RFC 4480                          RIPD                         July 2006   o  restless   o  sad   o  sarcastic   o  serious   o  shocked   o  shy   o  sick   o  sleepy   o  stressed   o  surprised   o  thirsty   o  unknown   o  worried   Example:     <mood>       <note>I'm ready for the bar BOF!</note>       <sleepy/>       <thirsty/>     </mood>3.6.  Place-is Element   The <place-is> element describes properties of the place the person   is currently at.  This offers the watcher an indication of what kind   of communication is likely to be successful.  Each major media type   has its own set of attributes.  Omitting the element indicates that   the property is unknown.   For audio, we define the following attributes:   noisy:  The person is in a place with a level of background noise      that makes audio communications difficult.   ok:  The environmental conditions are suitable for audio      communications.   quiet:  The person is in a place such as a library, restaurant, place      of worship, or theater that discourages noise, conversation, and      other distractions.   unknown:  The place attributes for audio are unknown.   For video, we define the following attributes:   toobright:  The person is in a bright place, sufficient for good      rendering on video.Schulzrinne, et al.         Standards Track                    [Page 12]

RFC 4480                          RIPD                         July 2006   ok:  The environmental conditions are suitable for video.   dark:  The person is in a dark place, and thus the camera may not be      able to capture a good image.   unknown:  The place attributes for video are unknown.   For text (real-time text and instant messaging), we define   uncomfortable:  Typing or other text entry is uncomfortable.   inappropriate:  Typing or other text entry is inappropriate, e.g.,      since the user is in a vehicle or house of worship.   ok:  The environmental conditions are suitable for text-based      communications.   unknown:  The place attributes for text are unknown.   This list can be augmented by free-text values in a note or   additional IANA-registered values (Section 7).   The <place-is> element contains other elements, e.g.,     <place-is>       <audio>         <noisy />       </audio>       <video>         <dark />       </video>     </place-is>   The <place-is> element MAY be qualified with the 'from' and 'until'   attributes as described inSection 3.1.3.7.  Place-type Element   The <place-type> element describes the type of place the person is   currently at.  This offers the watcher an indication of what kind of   communication is likely to be appropriate.  The initial set of values   is contained inRFC 4589 [12].   This list can be augmented by free-text values or additional IANA-   registered values as described inRFC 4589.Schulzrinne, et al.         Standards Track                    [Page 13]

RFC 4480                          RIPD                         July 2006   The <place-type> element is a choice of elements, as in     <place-type>          <pt:street/>     </place-type>   The <place-type> element MAY be qualified with the 'from' and 'until'   attributes as described inSection 3.1.3.8.  Privacy Element   The <privacy> element indicates which types of communication third   parties in the vicinity of the presentity are unlikely to be able to   intercept accidentally or intentionally.  This does not in any way   describe the privacy properties of the electronic communication   channel, e.g., properties of the encryption algorithm or the network   protocol used.   audio: Inappropriate individuals are not likely to overhear audio      communications.   text:  Inappropriate individuals are not likely to see text      communications.   unknown:  This information is unknown.   video:  Inappropriate individuals are not likely to see video      communications.      The <privacy> element can be used by logic executing on the      watcher or by a composer to filter, sort and label tuples.  For      example, a composer may have rules that limit the publication of      tuples labeled "private" to a select subset of the watchers.   The <privacy> element MAY be qualified with the 'from' and 'until'   attributes as described inSection 3.1.   Example:     <privacy>       <text/>       <audio/>     </privacy>Schulzrinne, et al.         Standards Track                    [Page 14]

RFC 4480                          RIPD                         July 20063.9.  Relationship Element   The <relationship> element extends <tuple> and designates the type of   relationship an alternate contact has with the presentity.  This   element is provided only if the tuple refers to somebody other than   the presentity.  Relationship values include "family", "friend",   "associate" (e.g., for a colleague), "assistant", "supervisor",   "self", and "unknown".  The default is "self".   If a relationship is indicated, the URI in the <contact> element   refers to the entity, such as the assistant, that has a relationship   to the presentity, not the presentity itself.   Like tuples without a <relationship> qualifier, the <contact> element   for tuples labeled with a relationship can contain either a   communication URI such as "im", "sip", "sips", "h323", "tel", or   "mailto", or a presence URI, such as "pres" or "sip".   Example:     <relationship>       <friend/>     </relationship>3.10.  Service Class   The <service-class> element extends <tuple> and designates the type   of service offered.   electronic:  Delivery of information by electronic means, i.e.,      without delivering physical objects.  Examples include telephone,      fax, email, instant messaging, and SMS.   postal:  Delivery by the postal service, e.g., as a letter, parcel,      or postcard.  Delivery could be to a post office box or central      mailroom rather than the presentity's office location, for      example.   courier:  Delivery by messenger, overnight delivery, or courier.      Courier-delivered messages are usually delivered to a receptionist      rather than, say, a mailroom or receiving department.   freight:  Delivery by freight carrier, typically of larger objects      that are not sent by postal mail or courier.  The recipient is      often the shipping department or a loading dock.   in-person:  Describes the coordinates for visits in person, as by a      visitor, i.e., usually somebody's office or residence.Schulzrinne, et al.         Standards Track                    [Page 15]

RFC 4480                          RIPD                         July 2006   unknown:  The type of service is unknown.   Electronic service is implied if omitted.  The service types   'postal', 'courier', 'freight', and 'in-person' MUST NOT be used   unless the contact URI is empty.  Additional data elements defined   elsewhere describe the physical service delivery address for the in-   person, postal, or delivery services.  Such addresses might be   specified in geospatial coordinates, civic addresses, or some   specialized address format, e.g., for interstellar addresses or a   company-specific delivery system.   Example:     <service-class><postal/></service-class>3.11.  Sphere Element   The <sphere> element designates the current state and role that the   person plays.  For example, it might describe whether the person is   in a work mode, at home, or participating in activities related to   some other organization such as the IETF or a church.  This document   does not define names for these spheres except for two common ones,   "work" and "home", as well as "unknown".   Spheres allow the person to easily turn on or off certain rules that   depend on what groups of people should be made aware of the person's   status.  For example, if the person is a Boy Scout leader, he might   set the sphere to "scouting" and then have a rule set that allows   other scout masters in his troop to see his presence status.  As soon   as he switches his status to "work", "home", or some other sphere,   the fellow scouts would lose access.   The <sphere> element MAY be qualified with the 'from' and 'until'   attributes as described inSection 3.1.   Example:     <sphere>       <home/>     </sphere>3.12.  Status-Icon Element   The <status-icon> element includes a URI pointing to an image (icon)   representing the current status of the person or service.  The   watcher MAY use this information to represent the status in a   graphical user interface.  Presentities SHOULD provide images ofSchulzrinne, et al.         Standards Track                    [Page 16]

RFC 4480                          RIPD                         July 2006   sizes and aspect ratios that are appropriate for rendering as an   icon.  Support for JPEG, PNG, and GIF formats is RECOMMENDED.   Watchers resolving the URI MUST validate whether the local copy of   the icon is current when receiving a notification, using the standard   cache control mechanism in the URI-identified retrieval protocol.   Example:     <status-icon>http://www.example.com/playing.gif</status-icon>3.13.  Time Offset   The <time-offset> element describes the number of minutes of offset   from UTC at the person's current location.  A positive number   indicates that the local time-of-day is ahead (i.e., east of)   Universal Time, while a negative number indicates that the local   time-of-day is behind (i.e., west of) Universal Time.  Transitions   into and out of daylight savings time may temporarily cause a   difference between the true offset from UTC and the time offset   element.   An optional attribute, description, can be used to describe the   offset, e.g., by labeling the time zone.  This description is meant   for human consumption.   Publishers on mobile devices SHOULD NOT publish this information   unless they know the time offset information to reflect the current   location.  (For example, many laptop users do not update their time   zone when traveling.)  Publishers SHOULD update the information   whenever they discover that their UTC offset has changed.   Example:     <time-offset description="America/New_York">-300     </time-offset>3.14.  User-Input Element   The <user-input> element records the user-input or usage state of the   service or device, based on human user input, e.g., keyboard,   pointing device, or voice.  If contained in a <person> element, it   summarizes any user input activity across all services and devices   operated by the presentity.  The mechanism for such aggregation is   beyond the scope of this document, but generally reflects the most   recent user input across all devices and services.  The element can   assume one of two values, namely, 'active' or 'idle', with an   optional 'last-input' attribute that records when the last user inputSchulzrinne, et al.         Standards Track                    [Page 17]

RFC 4480                          RIPD                         July 2006   was received.  An optional 'idle-threshold' element records how long   the presentity will wait before reporting the service or device to be   idle, measured in seconds.   (A two-state model was chosen since it would otherwise be necessary   to send repeated last-input updates during continuous activity.)   A service that wants to indicate user input activity sends a <user-   input> 'active' indication when the user has provided user input   within a configurable interval of time, the idle-threshold.  If the   user ceases to provide input and the idle-threshold has elapsed, the   tuple is marked with a <user-input> 'idle' indication instead,   optionally including the time of last activity in the 'last-input'   attribute.  An example is below:     <user-input idle-threshold="600"       last-input="2004-10-21T13:20:00.000-05:00">idle</user-input>   Depending on device or service capabilities, user input may be   detected only for a particular application, i.e., when the   application has user focus or when a user has sent a message or   placed a call, or can be based on user input across all applications   running on one end system.   The <user-input> element may be used by a watcher, typically in   combination with other data, to estimate how likely a user is to   answer when contacting the service.  A tuple that has not been used   in a while may still be OPEN, but a watcher may choose to first   contact a URI in a tuple that is both OPEN and has been used more   recently.   The <user-input> attribute can be omitted if the presentity wants to   indicate that the device has not been used for a while, but does not   want to reveal the precise duration, as in the following:     <user-input>idle</user-input>   Configuration MUST include the option to omit the 'last-input'   attribute.4.  Example   The example below describes the presentity   'pres:someone@example.com', which has a SIP contact,   'sip:someone@example.com', representing a service.  It also has a   device contact, as an email box.  The presentity is in a meeting, in   a public office setting.  The 'until' information indicates that he   will be there until 5:30 pm local time.  The presentity also has anSchulzrinne, et al.         Standards Track                    [Page 18]

RFC 4480                          RIPD                         July 2006   assistant, sip:secretary@example.com, who happens to be available for   communications.    <?xml version="1.0" encoding="UTF-8"?>      <presence xmlns="urn:ietf:params:xml:ns:pidf"        xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"        xmlns:lt="urn:ietf:params:xml:ns:location-type"        xmlns:rpid="urn:ietf:params:xml:ns:pidf:rpid"        entity="pres:someone@example.com">     <tuple>       <status>         <basic>open</basic>       </status>       <dm:deviceID>urn:device:0003ba4811e3</dm:deviceID>       <rpid:relationship><rpid:self/></rpid:relationship>       <rpid:service-class><rpid:electronic/></rpid:service-class>       <contact priority="0.8">im:someone@mobile.example.net</contact>       <note xml:lang="en">Don't Disturb Please!</note>       <note xml:lang="fr">Ne derangez pas, s'il vous plait</note>       <timestamp>2005-10-27T16:49:29Z</timestamp>     </tuple>     <tuple>       <status>         <basic>open</basic>       </status>       <rpid:relationship><rpid:assistant/></rpid:relationship>       <contact priority="1.0">mailto:secretary@example.com</contact>     </tuple>     <tuple>       <status>         <basic>open</basic>       </status>       <dm:deviceID>urn:x-mac:0003ba4811e3</dm:deviceID>       <rpid:class>email</rpid:class>       <rpid:service-class><rpid:electronic/></rpid:service-class>       <rpid:status-icon>http://example.com/mail.png</rpid:status-icon>       <contact priority="1.0">mailto:someone@example.com</contact>     </tuple>     <note>I'll be in Tokyo next week</note>     <dm:device>       <rpid:user-input idle-threshold="600"         last-input="2004-10-21T13:20:00-05:00">idle</rpid:user-input>       <dm:deviceID>urn:device:0003ba4811e3</dm:deviceID>Schulzrinne, et al.         Standards Track                    [Page 19]

RFC 4480                          RIPD                         July 2006       <dm:note>PC</dm:note>     </dm:device>     <dm:person>       <rpid:activities from="2005-05-30T12:00:00+05:00"          until="2005-05-30T17:00:00+05:00">          <rpid:note>Far away</rpid:note>          <rpid:away/>       </rpid:activities>       <rpid:class>calendar</rpid:class>       <rpid:mood>         <rpid:angry/>         <rpid:other>brooding</rpid:other>       </rpid:mood>       <rpid:place-is>          <rpid:audio>             <rpid:noisy/>          </rpid:audio>       </rpid:place-is>       <rpid:place-type><lt:residence/></rpid:place-type>       <rpid:privacy><rpid:unknown/></rpid:privacy>       <rpid:sphere>bowling league</rpid:sphere>       <rpid:status-icon>http://example.com/play.gif</rpid:status-icon>       <rpid:time-offset>-240</rpid:time-offset>       <dm:note>Scoring 120</dm:note>       <dm:timestamp>2005-05-30T16:09:44+05:00</dm:timestamp>     </dm:person>   </presence>5.  XML Schema Definitions   The RPID schema is shown below.  Due to limitations in composing   schemas, not all XML documents that validate against the schema below   are semantically valid RPID documents.  In particular, the schema   allows each element to appear anyhere in PIDF or data-model elements;   Table 1 restricts where these elements can appear for semantically   valid RPID documents.  Elements that do not have from/until   parameters MUST NOT appear more than once in each <person>, <tuple>,   or <device>.5.1.  urn:ietf:params:xml:ns:pidf:rpid   <?xml version="1.0" encoding="UTF-8"?>   <xs:schema targetNamespace="urn:ietf:params:xml:ns:pidf:rpid"      xmlns="urn:ietf:params:xml:ns:pidf:rpid"      xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"      xmlns:xs="http://www.w3.org/2001/XMLSchema"Schulzrinne, et al.         Standards Track                    [Page 20]

RFC 4480                          RIPD                         July 2006      elementFormDefault="qualified"      attributeFormDefault="unqualified">     <xs:simpleType name="activeIdle">       <xs:restriction base="xs:string">         <xs:enumeration value="active"/>         <xs:enumeration value="idle"/>       </xs:restriction>     </xs:simpleType>     <xs:element name="activities">       <xs:annotation>         <xs:documentation>           Describes what the person is currently doing, expressed as           an enumeration of activity-describing elements.  A person           can be engaged in multiple activities at the same time,           e.g., traveling and having a meal.         </xs:documentation>       </xs:annotation>       <xs:complexType>         <xs:sequence>           <xs:element name="note" type="Note_t" minOccurs="0"              maxOccurs="unbounded" />           <xs:choice>             <xs:element name="unknown" type="empty" minOccurs="0"/>             <xs:sequence maxOccurs="unbounded">               <xs:choice>                 <xs:element name="appointment"                   type="empty" />                 <xs:element name="away"                   type="empty" />                 <xs:element name="breakfast"                   type="empty" />                 <xs:element name="busy"                   type="empty" />                 <xs:element name="dinner"                   type="empty" />                 <xs:element name="holiday"                   type="empty" />                 <xs:element name="in-transit"                   type="empty" />                 <xs:element name="looking-for-work"                   type="empty" />                 <xs:element name="meal"                   type="empty" />                 <xs:element name="meeting"                   type="empty" />Schulzrinne, et al.         Standards Track                    [Page 21]

RFC 4480                          RIPD                         July 2006                 <xs:element name="on-the-phone"                   type="empty" />                 <xs:element name="performance"                   type="empty" />                 <xs:element name="permanent-absence"                   type="empty" />                 <xs:element name="playing"                   type="empty" />                 <xs:element name="presentation"                   type="empty" />                 <xs:element name="shopping"                   type="empty" />                 <xs:element name="sleeping"                   type="empty" />                 <xs:element name="spectator"                   type="empty" />                 <xs:element name="steering"                   type="empty" />                 <xs:element name="travel"                   type="empty" />                 <xs:element name="tv"                   type="empty" />                 <xs:element name="vacation"                   type="empty" />                 <xs:element name="working"                   type="empty" />                 <xs:element name="worship"                   type="empty" />                 <xs:element name="other"                   type="Note_t" />                 <xs:any namespace="##other"                   maxOccurs="unbounded" processContents="lax"/>               </xs:choice>             </xs:sequence>           </xs:choice>         </xs:sequence>         <xs:attributeGroup ref="fromUntil"/>         <xs:attribute name="id" type="xs:ID"/>         <xs:anyAttribute namespace="##any" processContents="lax"/>       </xs:complexType>     </xs:element>     <xs:element name="class" type="xs:token">       <xs:annotation>         <xs:documentation>           Describes the class of the service, device or person.         </xs:documentation>       </xs:annotation>Schulzrinne, et al.         Standards Track                    [Page 22]

RFC 4480                          RIPD                         July 2006     </xs:element>     <xs:element name="mood">       <xs:annotation>         <xs:documentation>           Describes the mood of the presentity.         </xs:documentation>       </xs:annotation>       <xs:complexType>         <xs:sequence>           <xs:element name="note" type="Note_t" minOccurs="0"           maxOccurs="unbounded" />           <xs:choice>             <xs:element name="unknown" type="empty"/>             <xs:sequence maxOccurs="unbounded">               <xs:choice>                 <xs:element name="afraid"                   type="empty"/>                 <xs:element name="amazed"                   type="empty"/>                 <xs:element name="angry"                   type="empty"/>                 <xs:element name="annoyed"                   type="empty"/>                 <xs:element name="anxious"                   type="empty" />                 <xs:element name="ashamed"                   type="empty" />                 <xs:element name="bored"                   type="empty" />                 <xs:element name="brave"                   type="empty" />                 <xs:element name="calm"                   type="empty" />                 <xs:element name="cold"                   type="empty" />                 <xs:element name="confused"                   type="empty" />                 <xs:element name="contented"                   type="empty" />                 <xs:element name="cranky"                   type="empty" />                 <xs:element name="curious"                   type="empty" />                 <xs:element name="depressed"                   type="empty" />                 <xs:element name="disappointed"                   type="empty" />Schulzrinne, et al.         Standards Track                    [Page 23]

RFC 4480                          RIPD                         July 2006                 <xs:element name="disgusted"                   type="empty" />                 <xs:element name="distracted"                   type="empty" />                 <xs:element name="embarrassed"                   type="empty" />                 <xs:element name="excited"                   type="empty" />                 <xs:element name="flirtatious"                   type="empty" />                 <xs:element name="frustrated"                   type="empty" />                 <xs:element name="grumpy"                   type="empty" />                 <xs:element name="guilty"                   type="empty" />                 <xs:element name="happy"                   type="empty" />                 <xs:element name="hot"                   type="empty" />                 <xs:element name="humbled"                   type="empty" />                 <xs:element name="humiliated"                   type="empty" />                 <xs:element name="hungry"                   type="empty" />                 <xs:element name="hurt"                   type="empty" />                 <xs:element name="impressed"                   type="empty" />                 <xs:element name="in_awe"                   type="empty" />                 <xs:element name="in_love"                   type="empty" />                 <xs:element name="indignant"                   type="empty" />                 <xs:element name="interested"                   type="empty" />                 <xs:element name="invincible"                   type="empty" />                 <xs:element name="jealous"                   type="empty" />                 <xs:element name="lonely"                   type="empty" />                 <xs:element name="mean"                   type="empty" />                 <xs:element name="moody"                   type="empty" />Schulzrinne, et al.         Standards Track                    [Page 24]

RFC 4480                          RIPD                         July 2006                 <xs:element name="nervous"                   type="empty" />                 <xs:element name="neutral"                   type="empty" />                 <xs:element name="offended"                   type="empty" />                 <xs:element name="playful"                   type="empty" />                 <xs:element name="proud"                   type="empty" />                 <xs:element name="relieved"                   type="empty" />                 <xs:element name="remorseful"                   type="empty" />                 <xs:element name="restless"                   type="empty" />                 <xs:element name="sad"                   type="empty" />                 <xs:element name="sarcastic"                   type="empty" />                 <xs:element name="serious"                   type="empty" />                 <xs:element name="shocked"                   type="empty" />                 <xs:element name="shy"                   type="empty" />                 <xs:element name="sick"                   type="empty" />                 <xs:element name="sleepy"                   type="empty" />                 <xs:element name="stressed"                   type="empty" />                 <xs:element name="surprised"                   type="empty" />                 <xs:element name="thirsty"                   type="empty" />                 <xs:element name="worried"                   type="empty" />                 <xs:element name="other"                   type="Note_t" />                 <xs:any namespace="##other"                   maxOccurs="unbounded" processContents="lax"/>               </xs:choice>             </xs:sequence>           </xs:choice>         </xs:sequence>         <xs:attributeGroup ref="fromUntil"/>         <xs:attribute name="id" type="xs:ID"/>Schulzrinne, et al.         Standards Track                    [Page 25]

RFC 4480                          RIPD                         July 2006         <xs:anyAttribute namespace="##any" processContents="lax"/>       </xs:complexType>     </xs:element>     <xs:element name="place-is">       <xs:complexType>         <xs:sequence>           <xs:element name="note" type="Note_t" minOccurs="0"              maxOccurs="unbounded" />           <xs:element name="audio" minOccurs="0">             <xs:complexType>               <xs:choice>                 <xs:element name="noisy" type="empty" />                 <xs:element name="ok" type="empty" />                 <xs:element name="quiet" type="empty" />                 <xs:element name="unknown" type="empty" />               </xs:choice>             </xs:complexType>           </xs:element>           <xs:element name="video" minOccurs="0">             <xs:complexType>               <xs:choice>                 <xs:element name="toobright" type="empty" />                 <xs:element name="ok" type="empty" />                 <xs:element name="dark" type="empty" />                 <xs:element name="unknown" type="empty" />               </xs:choice>             </xs:complexType>           </xs:element>           <xs:element name="text" minOccurs="0">             <xs:complexType>               <xs:choice>                 <xs:element name="uncomfortable" type="empty" />                 <xs:element name="inappropriate" type="empty" />                 <xs:element name="ok" type="empty" />                 <xs:element name="unknown" type="empty" />               </xs:choice>             </xs:complexType>           </xs:element>         </xs:sequence>         <xs:attributeGroup ref="fromUntil"/>         <xs:attribute name="id" type="xs:ID"/>         <xs:anyAttribute namespace="##any" processContents="lax"/>       </xs:complexType>     </xs:element>    <xs:element name="place-type">        <xs:annotation>Schulzrinne, et al.         Standards Track                    [Page 26]

RFC 4480                          RIPD                         July 2006          <xs:documentation>            Describes the type of place the person is currently at.          </xs:documentation>        </xs:annotation>        <xs:complexType>          <xs:sequence>            <xs:element name="note" type="Note_t" minOccurs="0"               maxOccurs="unbounded" />            <xs:choice>              <xs:element name="other" type="Note_t"/>              <xs:any namespace="##other" maxOccurs="unbounded"                processContents="lax"/>            </xs:choice>          </xs:sequence>          <xs:attributeGroup ref="fromUntil"/>          <xs:attribute name="id" type="xs:ID"/>          <xs:anyAttribute namespace="##any" processContents="lax"/>        </xs:complexType>      </xs:element>     <xs:element name="privacy">       <xs:annotation>          <xs:documentation>            Indicates which type of communication third parties in the            vicinity of the presentity are unlikely to be able to            intercept accidentally or intentionally.          </xs:documentation>       </xs:annotation>       <xs:complexType>         <xs:sequence>           <xs:element name="note" type="Note_t" minOccurs="0"              maxOccurs="unbounded" />           <xs:choice>             <xs:element name="unknown" type="empty"/>             <xs:sequence minOccurs="1">               <xs:element name="audio" type="empty" minOccurs="0"/>               <xs:element name="text" type="empty" minOccurs="0"/>               <xs:element name="video" type="empty" minOccurs="0"/>               <xs:any namespace="##other" minOccurs="0"                  maxOccurs="unbounded" processContents="lax"/>             </xs:sequence>           </xs:choice>         </xs:sequence>         <xs:attributeGroup ref="fromUntil"/>         <xs:attribute name="id" type="xs:ID"/>         <xs:anyAttribute namespace="##any" processContents="lax"/>       </xs:complexType>     </xs:element>Schulzrinne, et al.         Standards Track                    [Page 27]

RFC 4480                          RIPD                         July 2006     <xs:element name="relationship">         <xs:annotation>            <xs:documentation>              Designates the type of relationship an alternate contact              has with the presentity.            </xs:documentation>         </xs:annotation>         <xs:complexType>           <xs:sequence>             <xs:element name="note" type="Note_t" minOccurs="0"                maxOccurs="unbounded" />             <xs:choice>                <xs:element name="assistant" type="empty" />                <xs:element name="associate" type="empty" />                <xs:element name="family" type="empty" />                <xs:element name="friend" type="empty" />                <xs:element name="other" type="Note_t" minOccurs="0" />                <xs:element name="self" type="empty" />                <xs:element name="supervisor" type="empty" />                <xs:element name="unknown" type="empty" />                <xs:any namespace="##other" maxOccurs="unbounded"                  processContents="lax"/>             </xs:choice>           </xs:sequence>         </xs:complexType>     </xs:element>     <xs:element name="service-class">       <xs:annotation>         <xs:documentation>           Designates the type of service offered.         </xs:documentation>       </xs:annotation>       <xs:complexType>         <xs:sequence>           <xs:element name="note" type="Note_t" minOccurs="0"              maxOccurs="unbounded" />           <xs:choice>             <xs:element name="courier" type="empty" />             <xs:element name="electronic" type="empty" />             <xs:element name="freight" type="empty" />             <xs:element name="in-person" type="empty" />             <xs:element name="postal" type="empty" />             <xs:element name="unknown" type="empty" />             <xs:any namespace="##other" maxOccurs="unbounded"               processContents="lax"/>           </xs:choice>         </xs:sequence>Schulzrinne, et al.         Standards Track                    [Page 28]

RFC 4480                          RIPD                         July 2006       </xs:complexType>     </xs:element>     <xs:element name="sphere">       <xs:annotation>         <xs:documentation>           Designates the current state and role that the person plays.         </xs:documentation>       </xs:annotation>       <xs:complexType>         <xs:choice minOccurs="0">           <xs:element name="home" type="empty" />           <xs:element name="work" type="empty" />           <xs:element name="unknown" type="empty" />           <xs:any namespace="##other" maxOccurs="unbounded"              processContents="lax"/>         </xs:choice>         <xs:attributeGroup ref="fromUntil"/>         <xs:attribute name="id" type="xs:ID"/>         <xs:anyAttribute namespace="##any" processContents="lax"/>       </xs:complexType>     </xs:element>     <xs:element name="status-icon">       <xs:annotation>         <xs:documentation>           A URI pointing to an image (icon) representing the current           status of the person or service.         </xs:documentation>       </xs:annotation>       <xs:complexType>         <xs:simpleContent>           <xs:extension base="xs:anyURI">             <xs:attributeGroup ref="fromUntil"/>             <xs:attribute name="id" type="xs:ID"/>             <xs:anyAttribute namespace="##any" processContents="lax"/>           </xs:extension>         </xs:simpleContent>       </xs:complexType>     </xs:element>     <xs:element name="time-offset">       <xs:annotation>         <xs:documentation>           Describes the number of minutes of offset from UTC at the           user's current location.         </xs:documentation>       </xs:annotation>Schulzrinne, et al.         Standards Track                    [Page 29]

RFC 4480                          RIPD                         July 2006       <xs:complexType>         <xs:simpleContent>           <xs:extension base="xs:integer">             <xs:attributeGroup ref="fromUntil"/>             <xs:attribute name="description"                type="xs:string"/>             <xs:attribute name="id" type="xs:ID"/>             <xs:anyAttribute namespace="##any" processContents="lax"/>           </xs:extension>         </xs:simpleContent>       </xs:complexType>     </xs:element>     <xs:element name="user-input">       <xs:annotation>         <xs:documentation>           Records the user-input or usage state of the service or           device.         </xs:documentation>       </xs:annotation>       <xs:complexType>           <xs:simpleContent>             <xs:extension base="activeIdle">               <xs:attribute name="idle-threshold"                 type="xs:positiveInteger"/>               <xs:attribute name="last-input" type="xs:dateTime"/>               <xs:attribute name="id" type="xs:ID"/>               <xs:anyAttribute namespace="##any"                 processContents="lax"/>             </xs:extension>           </xs:simpleContent>       </xs:complexType>     </xs:element>   </xs:schema>6.  Extending RPID   Any developer can introduce their own element names, avoiding   conflict by choosing an appropriate namespace URI.  To add new   standardized elements to the enumerations <activities>, <mood>,   <privacy>, <relationship> and <service-class>, the extension process   described in PIDF [9] is followed, i.e., such extensions would use   namespace designators such as urn:ietf:params:xml:ns:pidf:ext, where   'ext' is the name of the extension.  Any new values for the <place-   type> element are assigned according to [12] and are given a   namespace designator at their time of registration.Schulzrinne, et al.         Standards Track                    [Page 30]

RFC 4480                          RIPD                         July 2006   To avoid the unnecessary proliferation of XML namespaces containing a   single element, groups of element registrations for each of these   enumerations, such as <privacy>, SHOULD be bundled into a single   namespace rather than assigning a new namespace to each new element.7.  IANA Considerations7.1.  URN Sub-Namespace Registration for      'urn:ietf:params:xml:ns:pidf:rpid'   URI:  urn:ietf:params:xml:ns:pidf:rpid   Description:  This is the XML namespace for XML elements defined byRFC 4480 to describe rich presence information extensions for the      status element in the PIDF presence document format in the      application/pidf+xml content type.   Registrant Contact:  IETF, SIMPLE working group, simple@ietf.org,      Henning Schulzrinne, hgs@cs.columbia.edu   XML:    BEGIN      <?xml version="1.0"?>      <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"      "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">      <html xmlns="http://www.w3.org/1999/xhtml      <head>           <meta http-equiv="content-type"           content="text/html;charset=iso-8859-1"/>           <title>RPID: Rich Presence Extensions to the Presence             Information Data Format (PIDF)</title>      </head>      <body>          <h1>Namespace for rich presence extension</h1>          <h2>urn:ietf:params:xml:ns:pidf:rpid</h2>          <p>See <a href="http://www.rfc-editor.org/rfc/rfc4480.txt">              RFC&4480;</a>.</p>       </body>       </html>      ENDSchulzrinne, et al.         Standards Track                    [Page 31]

RFC 4480                          RIPD                         July 20067.2.  Schema Registration for Schema      'urn:ietf:params:xml:ns:pidf:status:rpid'   URI:  urn:ietf:params:xml:ns:pidf:status:rpid   Registrant Contact:  IESG   XML:  SeeSection 5   Note that this document does not need a new content type.  It   inherits the content type from [8], namely, application/pidf+xml.8.  Internationalization Considerations   RPID contains mostly tokens that are meant for consumption by   programs, not directly by humans.  Programs are expected to translate   those tokens into language-appropriate text strings according to the   preferences of the watcher.   Some elements may contain <note> and <other> elements that can   contain free text.  These elements SHOULD be labeled with the 'xml:   lang' attribute to indicate their language and script.  The   specification allows multiple occurrences of these elements so that   the presentity can convey <note> and <other> elements in multiple   scripts and languages.  If no 'xml:lang' attribute is provided, the   default value is "i-default" [3].   Since RPID is represented in XML, it provides native support for   encoding information using the Unicode character set and its more   compact representations including UTF-8.  Conformant XML processors   recognize both UTF-8 and UTF-16.  Though XML includes provisions to   identify and use other character encodings through use of an   "encoding" attribute in an <?xml?> declaration, use of UTF-8 is   RECOMMENDED in environments where parser encoding support   incompatibility exists.   A description of time-zone considerations can be found inSection 3.13.9.  Security Considerations   The security considerations in [8] apply, as well as [7].  Compared   to PIDF, this presence document format reveals additional information   about presentities that can be highly sensitive.  Beyond traditional   security measures to protect confidentiality and integrity, systems   should offer a means to selectively reveal information to particular   watchers and to inspect the information that is being published,   particularly if it is generated automatically from other sources,   such as calendars or sensors.Schulzrinne, et al.         Standards Track                    [Page 32]

RFC 4480                          RIPD                         July 2006   Like any reference to an external object, the <status-icon> may allow   the presentity to induce the watcher to retrieve data from a third   party (content indirection attack), thus either retrieving harmful   content or adding to the server load of the referenced resource.10.  References10.1.  Normative References   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement         Levels",BCP 14,RFC 2119, March 1997.   [2]   Moats, R., "URN Syntax",RFC 2141, May 1997.   [3]   Alvestrand, H., "IETF Policy on Character Sets and Languages",BCP 18,RFC 2277, January 1998.   [4]   Moats, R., "A URN Namespace for IETF Documents",RFC 2648,         August 1999.   [5]   Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence         and Instant Messaging",RFC 2778, February 2000.   [6]   Mealling, M., "The IETF XML Registry",BCP 81,RFC 3688,         January 2004.   [7]   Rosenberg, J., "A Presence Event Package for the Session         Initiation Protocol (SIP)",RFC 3856, August 2004.   [8]   Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr, W., and         J. Peterson, "Presence Information Data Format (PIDF)",RFC3863, August 2004.   [9]   Yergeau, F., Paoli, J., Sperberg-McQueen, C., Bray, T., and E.         Maler, "Extensible Markup Language (XML) 1.0 (Third Edition),"         W3C REC REC-xml-20040204, February 2004.   [10]  Maloney, M., Beech, D., Thompson, H., and N. Mendelsohn, "XML         Schema Part 1: Structures Second Edition", W3C REC REC-         xmlschema-1-20041028, October 2004.   [11]  Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes Second         Edition", W3C REC REC-xmlschema-2-20041028, October 2004.   [12]  Schulzrinne, H. and H. Tschofenig, "Location Types Registry",RFC 4589, July 2006.Schulzrinne, et al.         Standards Track                    [Page 33]

RFC 4480                          RIPD                         July 200610.2.  Informative References   [13]  Dawson, F. and D. Stenerson, "Internet Calendaring and         Scheduling Core Object Specification (iCalendar)",RFC 2445,         November 1998.   [14]  Peterson, J., "Common Profile for Instant Messaging (CPIM)",RFC 3860, August 2004.   [15]  Lennox, J., Wu, X., and H. Schulzrinne, "Call Processing         Language (CPL): A Language for User Control of Internet         Telephony Services",RFC 3880, October 2004.   [16]  Rosenberg, J., "A Data Model for Presence",RFC 4479, July         2006.   [17]  Lisetti, C., "Personality, Affect, and Emotion Taxonomy for         Socially Intelligent Agents", Proceedings of FLAIRS 2002, 2002.   [18]  Open Mobile Alliance, "The Wireless Village Initiative:         Presence Attributes 1.1", Recommendation WV-29, 2004.Schulzrinne, et al.         Standards Track                    [Page 34]

RFC 4480                          RIPD                         July 2006Appendix A.  Acknowledgements   The document reflects the discussion on the SIMPLE mailing list, with   contributions from many individuals.  David L. Black, Miguel Garcia,   Avshalom Houri, Markus Isomaki, Rick Jones, Hisham Khartabil,   Jonathan Lennox, Eva-Maria Leppanen, Mikko Lonnfors, Rohan Mahy,   Miguel Marcia, Andrew Newton, Aki Niemi, Jon Peterson, and Brian   Rosen provided detailed comments and suggestions.  Xiaotao Wu   assisted with schema testing.  Jari Urpalainen provided valuable   advice on XML schema issues.Schulzrinne, et al.         Standards Track                    [Page 35]

RFC 4480                          RIPD                         July 2006Authors' Addresses   Henning Schulzrinne   Columbia University   Department of Computer Science   450 Computer Science Building   New York, NY  10027   US   Phone: +1 212 939 7042   EMail: hgs+simple@cs.columbia.edu   URI:http://www.cs.columbia.edu   Vijay Gurbani   Lucent   2000 Naperville Rd.   Room 6G-440   Naperville, IL  60566-7033   US   EMail: vkg@lucent.com   Paul Kyzivat   Cisco Systems   BXB500 C2-2   1414 Massachusetts Avenue   Boxborough, MA  01719   US   EMail: pkyzivat@cisco.com   Jonathan Rosenberg   Cisco Systems   600 Lanidex Plaza   Parsippany, NJ  07054-2711   US   EMail: jdrosen@cisco.comSchulzrinne, et al.         Standards Track                    [Page 36]

RFC 4480                          RIPD                         July 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Schulzrinne, et al.         Standards Track                    [Page 37]

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