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Network Working Group                                        M. LonnforsRequest for Comments: 5196                                       K. KissCategory: Standards Track                                          Nokia                                                          September 2008Session Initiation Protocol (SIP) User Agent Capability Extension toPresence 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.Abstract   Presence Information Data Format (PIDF) defines a common presence   data format for Common Profile for Presence (CPP) compliant presence   protocols.  This memo defines a PIDF extension to represent SIP User   Agent capabilities.Lonnfors & Kiss             Standards Track                     [Page 1]

RFC 5196         User Agent Capability Presence Status    September 2008Table of Contents1. Introduction ....................................................31.1. Motivation .................................................31.2. Scope ......................................................42. Conventions .....................................................4   3. Extension for "Indicating User Agent Capabilities in the      Session Initiation Protocol (SIP)" in PIDF Documents ............43.1. Overview of Operation ......................................43.2. Service capabilities .......................................53.2.1. <servcaps> Element ..................................53.2.2. <audio> Element .....................................53.2.3. <application> Element ...............................53.2.4. <data> Element ......................................63.2.5. <control> Element ...................................63.2.6. <video> Element .....................................63.2.7. <text> Element ......................................63.2.8. <message> Element ...................................73.2.9. <type> Element ......................................73.2.10. <automata> Element .................................73.2.11. <class> Element ....................................73.2.12. <duplex> Element ...................................83.2.13. <description> Element ..............................83.2.14. <event-packages> Element ...........................93.2.15. <priority> Element .................................93.2.16. <methods> Element .................................103.2.17. <extensions> Element ..............................113.2.18. <schemes> Element .................................113.2.19. <actor> Element ...................................123.2.20. <isfocus> Element .................................123.2.21. <languages> Element ...............................133.3. Device Capabilities .......................................133.3.1. <devcaps> Element ..................................133.3.2. <mobility> Element .................................143.3.3. <description> Element ..............................144. Usage Guidelines ...............................................154.1. Use of <supported> and <notsupported> Elements ............155. Examples .......................................................166. XML Schema Definitions .........................................177. IANA Considerations ............................................267.1. URN Sub-Namespace Registration for ........................267.2. Schema Registration for Schema ............................278. Security Considerations ........................................279. Acknowledgments ................................................2710. References ....................................................2710.1. Normative References .....................................2710.2. Informative References ...................................28Lonnfors & Kiss             Standards Track                     [Page 2]

RFC 5196         User Agent Capability Presence Status    September 20081.  Introduction   Common Profile for Presence (CPP) [RFC3859] and Common Profile for   Instant Messaging (CPIM) [RFC3860] define common operations and   formats that all presence and instant messaging services must agree   upon so that basic interoperability is possible.  The actual base   format for the presence is defined in the Presence Information   Document Format (PIDF) [RFC3863].  The PIDF has been designed to   reduce the need for gatewaying and to allow end-to-end security of   presence information.  It has taken a very minimalistic approach to   support such operations.  In order to make the PIDF usable by   different presence applications, these applications usually must   extend the basic PIDF by standard XML mechanisms as defined in PIDF   [RFC3863].   The aim of this memo is to introduce a SIP-specific extension   mechanism to the PIDF that conveys the same SIP media feature tags as   described in [RFC3840].  With this extension, presence applications   based on SIP can have richer and more usable presence information   compared to the baseline PIDF.1.1.  Motivation   The PIDF [RFC3863] defines a <contact> element that may appear once   inside every <tuple> element.  The content of the <contact> element   encodes the CONTACT ADDRESS and CONTACT MEANS as defined in   [RFC2778].  The <contact> element is defined to be a URI of any   scheme.  In some implementations, the URI scheme can uniquely   identify the service the tuple intends to describe (e.g., im: URI   scheme usually represents Instant Messaging service).  However, this   may not be the case in all implementations.  For example in SIP, a   SIP URI scheme can represent different kinds of services.  A SIP URI   scheme can be used to contact voice services, video services, or   messaging services.  If it is not known by other means, it might be   hard for applications processing the presence information containing   only a SIP URI contact addresses to know what particular service the   tuple intends to describe.  Also, watchers receiving presence   information would probably benefit from getting more descriptive   information about what particular communication means or services are   supported by the presentity.   The User Agent Capabilities extension [RFC3840] defines a set of   extensions that allow user agents to express preferences about   request handling in SIP servers.  The same information can provide   value to watchers as well so that they can make more rational   decisions on how a presentity should be contacted if a presence   document contained this information.Lonnfors & Kiss             Standards Track                     [Page 3]

RFC 5196         User Agent Capability Presence Status    September 20081.2.  Scope   This document defines a PIDF extension, which enables SIP presence   implementations to represent User Agent Capabilities [RFC3840] within   presence information.   This extension does not replace media negotiation mechanisms defined   for SIP (e.g., SDP [RFC4566]).  The purpose of this extension is for   a presentity to give watchers hints about the presentity's   preferences, willingness, and capabilities to communicate before   watchers initiate communication with the presentity.2.  Conventions   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described in [RFC2119].   This memo makes use of the vocabulary defined in [RFC2778] and   [RFC3863].3.  Extension for "Indicating User Agent Capabilities in the Session    Initiation Protocol (SIP)" in PIDF Documents   This section presents the extension elements, attributes, their   values, and semantics.  This section also describes how this   extension can be further extended.   This extension is intended to be used within the PIDF [RFC3863] and   that particular usage is described here.  This extension may also be   used with other XML documents if appropriate.3.1.  Overview of Operation   This document defines how the features presented in [RFC3840] can be   provided as part of presence information.  Additionally, this memo   includes the "type" feature tag [RFC2913], "message" media type   feature tag [RFC4569], and the "language" feature tag [RFC4646]   definitions.  Adding these features to the PIDF means mapping them to   an XML formatted structure.   The presence data model [RFC4479] defines presence information   consisting of three types of data elements: person, service, and   device.  This memo follows this model so that one XML extension is   defined to describe device capabilities and another one to describe   service capabilities.Lonnfors & Kiss             Standards Track                     [Page 4]

RFC 5196         User Agent Capability Presence Status    September 2008   The namespace URIs for elements defined by this document are URNs   using the namespace identifier 'ietf' defined by [RFC2648] and   extended by [RFC3688].   When these extension namespaces are congregated with the PIDF   document, the combined document MUST follow the same general   formatting rules as specified inSection 4.1 of [RFC3863].3.2.  Service capabilities   Elements belonging to service capabilities are used to describe   dynamic characteristics of a service.  These capabilities are   enclosed within the <servcaps> element which SHOULD be located in the   PIDF document as a child element of urn:ietf:params:xml:ns:pidf   namespace <tuple> [RFC3863] element.   The namespace identifier for these elements is:   urn:ietf:params:xml:ns:pidf:caps3.2.1.  <servcaps> Element   The root element of service capabilities is <servcaps>.  The root   element always has to be present.  This element can contain the   following child elements: <audio>, <application>, <data>, <control>,   <video>, <text>, <message>, <type>, <automata>, <class>, <duplex>,   <description>, <event-packages>, <priority>, <methods>, <extensions>,   <schemes>, <actor>, <isfocus>, and <languages> followed by any number   of optional extension elements from other namespaces.   A <servcaps> element can contain any number of optional extension   attributes from other namespaces.3.2.2.  <audio> Element   The <audio> element indicates that the service supports audio as a   streaming media type as defined in [RFC3840].   The <audio> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports audio   media type, and the value 'false' indicates that service does not   support audio media type.3.2.3.  <application> Element   The <application> element indicates that the service supports   application as a streaming media type as defined in [RFC3840].Lonnfors & Kiss             Standards Track                     [Page 5]

RFC 5196         User Agent Capability Presence Status    September 2008   The <application> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports   application media type, and the value 'false' indicates that service   does not support application media type.3.2.4.  <data> Element   The <data> element indicates that the service supports data as a   streaming media type as defined in [RFC3840].   The <data> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports data   media type, and the value 'false' indicates that service does not   support data media type.3.2.5.  <control> Element   The <control> element indicates that the service supports control as   a streaming media type as defined in [RFC3840].   The <control> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports control   media type, and the value 'false' indicates that service does not   support control media type.3.2.6.  <video> Element   The <video> element indicates that the service supports video as a   streaming media type as defined in [RFC3840].   The <video> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports video   media type, and the value 'false' indicates that service does not   support video media type.3.2.7.  <text> Element   The <text> element indicates that the service supports text as a   streaming media type as defined in [RFC3840].   The <text> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports text   media type, and the value 'false' indicates that service does not   support text media type.Lonnfors & Kiss             Standards Track                     [Page 6]

RFC 5196         User Agent Capability Presence Status    September 20083.2.8.  <message> Element   The <message> element indicates that the service supports messaging   as a streaming media type as defined in [RFC4569].   The <message> element is a boolean type and does not have any   attributes.  The value 'true' indicates that service supports message   media type, and the value 'false' indicates that service does not   support message media type.3.2.9.  <type> Element   The <type> element indicates a MIME media content type (i.e., that   appears in a 'Content-type:' header of the corresponding MIME-   formatted data) as defined in [RFC2913].   The <type> element is a string type and does not have any attributes.   It MUST be a string of the form "type/subtype", where 'type' and   'subtype' are defined by the MIME specification [RFC2045].  Only   lowercase letters SHOULD be used.3.2.10.  <automata> Element   The <automata> element indicates whether the service represents an   automaton (such as a voicemail server, conference server, or   recording device) or a human as defined in [RFC3840].   The <automata> element is a boolean type and does not have any   attributes.  The value 'true' indicates that the service represents   an automaton, and the value 'false' indicates that it represents a   human.3.2.11.  <class> Element   The <class> element indicates the setting, business or personal, in   which a communications service is used as defined in [RFC3840].   The <class> element can contain two elements: <supported> and   <notsupported>.  Classes that are supported by the service can be   listed under the <supported> element, and classes that are not   supported by the service can be listed under the <notsupported>   element.   <supported> and <notsupported> elements can contain <business> and   <personal> elements followed by any number of optional extension   elements from other namespaces.  The semantics of business and   personal are defined in [RFC3840] as:Lonnfors & Kiss             Standards Track                     [Page 7]

RFC 5196         User Agent Capability Presence Status    September 2008   o  <business>: The service is used for business communications.   o  <personal>: The service is used for personal communications.   Any value that is registered with IANA for the SIP media feature tag   registration tree as a sip.class media feature tag can be used as a   value of an extension element.  If the appropriate value is not   registered, it SHOULD be registered as defined in [RFC3840].3.2.12.  <duplex> Element   The <duplex> element lists whether a communications service can   simultaneously send and receive media ("full"), alternate between   sending and receiving ("half"), only receive ("receive-only"), or   only send ("send-only") as defined in [RFC3840].   The <duplex> element can contain two elements: <supported> and   <notsupported>.  Duplex modes that are supported by the service can   be listed under the <supported> element, and duplex modes that are   not supported by the service can be listed under the <notsupported>   element.   <supported> and <notsupported> elements can contain <full>, <half>,   <receive-only>, and <send-only> elements followed by any number of   optional extension elements from other namespaces.  The semantics of   these elements are defined in [RFC3840] as:   o  <full>: The service can simultaneously send and receive media.   o  <half>: The service can alternate between sending and receiving      media.   o  <receive-only>: The service can only receive media.   o  <send-only>: The service can only send media.   Any value that is registered with IANA for the SIP media feature tag   registration tree as a sip.duplex media feature tag can be used as a   value of an extension element.  If the appropriate value is not   registered, it SHOULD be registered as defined in [RFC3840].3.2.13.  <description> Element   The <description> element provides a textual description of the   service as defined in [RFC3840].   The <description> element is of string type and does not have any   attributes.Lonnfors & Kiss             Standards Track                     [Page 8]

RFC 5196         User Agent Capability Presence Status    September 2008   The <description> element SHOULD be labeled with the 'xml:lang'   attribute to indicate its language and script.  The specification   allows multiple occurrences of this elements so that the presentity   can convey <description> elements in multiple scripts and languages.   If no 'xml:lang' attribute is provided, the default value is   "i-default" as defined in [RFC2277].3.2.14.  <event-packages> Element   The <event-packages> element lists the event packages supported by a   service.   The <event-packages> element can contain two elements: <supported>   and <notsupported>.  Event packages that are supported by the service   can be listed under the <supported> element, and event packages that   are not supported by the service can be listed under the   <notsupported> element.   The <supported> and <notsupported> elements can contain any values   from the IANA SIP event types namespace registry followed by any   number of optional extension elements from other namespaces.  As of   this writing, the IANA SIP event types namespace registry includes   the following packages: <conference>, <dialog>, <kpml>,   <message-summary>, <poc-settings>, <presence>, <reg>, <refer>,   <Siemens-RTP-Stats>, <spirits-INDPs>, <spirits-user-prof>, and   <winfo>.3.2.15.  <priority> Element   The <priority> element indicates the call priorities the service is   willing to handle as defined in [RFC3840].   The <priority> element can contain two elements: <supported> and   <notsupported>.  Priority values that are supported by the service   can be listed under the <supported> element, and priority values that   are not supported by the service can be listed under the   <notsupported> element.   The <supported> and <notsupported> elements can contain any number of   <lowerthan>, <higherthan>, <equals>, and <range> elements followed by   any number of optional extension elements from other namespaces.3.2.15.1.  <lowerthan> Element   The <lowerthan> element has a single attribute called "maxvalue".   The "maxvalue" attribute is used to give the highest priority value   that the service is willing to support.  All values equal and below   that value are supported.Lonnfors & Kiss             Standards Track                     [Page 9]

RFC 5196         User Agent Capability Presence Status    September 20083.2.15.2.  <higherthan> Element   The <higherthan> element has a single attribute called "minvalue".   The "minvalue" attribute is used to give the lowest priority value   that the service is willing to support.  All values equal and above   that value are supported.3.2.15.3.  <equals> Element   The <equals> element is used to indicate the exact priority value   that the service is willing to handle.  The <equals> element has a   single attribute called "value".  The "value" attribute is used to   indicate the exact supported priority value.3.2.15.4.  <range> Element   The <range> element is used to indicate the priority range that the   service is willing to handle.  The <range> element has two attributes   called "minvalue" and "maxvalue".  The value of the "minvalue"   attribute indicates the lowest priority value supported by the   service, and the value of the "maxvalue" attribute indicates the   highest priority value supported by the service.3.2.16.  <methods> Element   The <methods> element indicates the SIP methods supported by a   service.  In this case, "supported" means that the service can   receive requests with this method.  In that sense, it has the same   connotation as the Allow header field as defined in [RFC3840].   The <methods> element can contain two elements: <supported> and   <notsupported>.  Methods that are supported by the service can be   listed under the <supported> element, and methods that are not   supported by the service can be listed under the <notsupported>   element.   The <supported> and <notsupported> elements can contain any values   from the methods table of the IANA SIP parameters registry table   followed by any number of optional extension elements from other   namespaces.  As of this writing, the IANA SIP parameters registry   includes the following methods:<ACK>, <BYE>, <CANCEL>, <INFO>,   <INVITE>, <MESSAGE>, <NOTIFY>, <OPTIONS>, <PRACK>, <PUBLISH>,   <REFER>, <REGISTER>, <SUBSCRIBE>, and <UPDATE>.Lonnfors & Kiss             Standards Track                    [Page 10]

RFC 5196         User Agent Capability Presence Status    September 20083.2.17.  <extensions> Element   The <extensions> element is a list of SIP extensions (each of which   is defined by an option-tag registered with IANA) that are understood   by the service.  Understood, in this context, means that the option   tag would be included in a Supported header field in a request as   defined in [RFC3840].   The <extensions> element can contain two elements: <supported> and   <notsupported>.  Extensions that are supported by the service can be   listed under the <supported> element, and extensions that are not   supported by the service can be listed under the <notsupported>   element.   The <supported> and <notsupported> elements can contain any values   from the option tags table of the IANA SIP parameters registry table   followed by any number of optional extension elements from other   namespaces.  As of this writing, the IANA SIP parameters registry   includes the following option tags: <rel100>, <early-session>,   <eventlist>, <from-change>, <gruu>, <histinfo>, <join>, <norefersub>,   <path>, <precondition>, <pref>, <privacy>, <recipient-list-invite>,   <recipient-list-subscribe>, <replaces>, <resource-priority>, <sdp-   anat>, <sec-agree>, <tdialog>, and <timer>.3.2.18.  <schemes> Element   The <schemes> element provides the set of URI schemes that are   supported by a service.  "Supported" implies, for example, that the   service would know how to handle a URI of that scheme in the Contact   header field of a redirect response as defined in [RFC3840].   The <schemes> element can contain two elements: <supported> and   <notsupported>.  Schemes that are supported by the service can be   listed under the <supported> element, and schemes that are not   supported by the service can be listed under the <notsupported>   element.   <supported> and <notsupported> elements can contain any number of <s>   elements, which can be used to describe individual schemes supported   by the service.3.2.18.1.  <s> Element   The <s> element is of string type and is used to describe an   individual scheme supported by the service.  Values that can be used   here are scheme names that are registered to the IANA URI scheme   registry.Lonnfors & Kiss             Standards Track                    [Page 11]

RFC 5196         User Agent Capability Presence Status    September 20083.2.19.  <actor> Element   The <actor> element indicates the type of entity that is available at   this URI as defined in [RFC3840].   The <actor> element can contain two elements: <supported> and   <notsupported>.  Actor types that are supported by the service can be   listed under the <supported> element, and actor types that are not   supported by the service can be listed under the <notsupported>   element.   The <supported> and <notsupported> elements can contain <principal>,   <attendant>, <msg-taker>, and <information> elements followed by any   number of optional extension elements from other namespaces.   The semantics of these elements are defined in [RFC3840] as:   o  <principal>: The service provides communication with the principal      that is associated with the service.  Often this will be a      specific human being, but it can be an automaton (for example,      when calling a voice portal).   o  <attendant>: The service provides communication with an automaton      or a person that will act as an intermediary in contacting the      principal associated with the service, or a substitute.   o  <msg-taker>: The service provides communication with an automaton      or a person that will take messages and deliver them to the      principal.   o  <information>: The service provides communication with an      automaton or a person that will provide information about the      principal.   Any value that is registered with IANA for the SIP media feature tag   registration tree as a sip.actor media feature tag can be used as a   value of an extension element.  If the appropriate value is not   registered, it SHOULD be registered as defined in [RFC3840].3.2.20.  <isfocus> Element   The <isfocus> element indicates that the service is a conference   server, also known as a focus as defined in [RFC3840].   The <isfocus> element is of boolean type and does not have any   attributes.  The value 'true' indicates that service is a conference   server and the value 'false' indicates that service does not support   conferencing.Lonnfors & Kiss             Standards Track                    [Page 12]

RFC 5196         User Agent Capability Presence Status    September 20083.2.21.  <languages> Element   The <languages> element indicates the ability to display particular   human languages as defined in [RFC4646].   The <languages> element can contain two elements: <supported> and   <notsupported>.  Languages that are supported by the service can be   listed under the <supported> element, and languages that are not   supported by the service can be listed under the <notsupported>   element.   <supported> and <notsupported> elements can contain any number of <l>   elements which can be used to describe individual languages supported   by the service.3.2.21.1.  <l> Element   The <l> element is of string type and is used to describe an   individual language supported by the service.  Values that can be   used here are language subtags that are registered to the IANA   language subtag registry as per [RFC4646].3.3.  Device Capabilities   Elements belonging to device capabilities are used to describe   dynamic characteristics of a device.  These capabilities are enclosed   within the <devcaps> element, which SHOULD be located in the PIDF   document as a child element of the   urn:ietf:params:xml:ns:pidf:data-model namespace <device> element   [RFC4479].   The namespace identifier for these elements is urn:   ietf:params:xml:ns:pidf:caps3.3.1.  <devcaps> Element   The root element of device capabilities is <devcaps>.  The root   element always has to be present.  This element can contain the   following child elements: <mobility> and <description> followed by   any number of optional extension elements from other namespaces.   A <devcaps> element can contain any number of optional extension   attributes from other namespaces.Lonnfors & Kiss             Standards Track                    [Page 13]

RFC 5196         User Agent Capability Presence Status    September 20083.3.2.  <mobility> Element   The <mobility> element indicates whether the device is fixed (meaning   that it is associated with a fixed point of contact with the network)   or mobile (meaning that it is not associated with a fixed point of   contact).  Note that cordless phones are fixed, not mobile, based on   this definition as defined in [RFC3840].   The <mobility> element can contain two elements: <supported> and   <notsupported>.  Mobility modes that are supported by the device can   be listed under the <supported> element and mobility modes that are   not supported by the device can be listed under the <notsupported>   element.   The <supported> and <notsupported> elements can contain <fixed> and   <mobile> elements followed by any number of optional extension   elements from other namespaces.   The semantics of these elements are defined in [RFC3840] as:   o  <fixed>: The device is stationary.   o  <mobile>: The device can move around with the user.   Any value that is registered with IANA to the SIP media feature tag   registration tree as sip.mobility media feature tag can be used as a   value of an extension element.  If the appropriate value is not   registered, it SHOULD be registered as defined in [RFC3840].3.3.3.  <description> Element   The <description> element provides a textual description of the   device as defined in [RFC3840].   The <description> element is of string type and does not have any   attributes.   The <description> element SHOULD be labeled with the 'xml:lang'   attribute to indicate its language and script.  The specification   allows multiple occurrences of this element so that the presentity   can convey <description> elements in multiple scripts and languages.   If no 'xml:lang' attribute is provided, the default value is   "i-default" as defined in [RFC2277].Lonnfors & Kiss             Standards Track                    [Page 14]

RFC 5196         User Agent Capability Presence Status    September 20084.  Usage Guidelines   The User Agent Capabilities extension [RFC3840] recommends that a UA   provides complete information in its contact predicate.  However, it   may be that the presentity is not willing to publish presence   information that would be consistent with actual device or service   capabilities (e.g., presentity may not want to indicate that he/she   supports voice when the service actually is able to support it).   Authorization rules or policies in the presence server may limit or   modify the presence information published by the presentity.  Also,   combining presence information from multiple sources may result in   loss or mismatch of information.   It is RECOMMENDED that Presence User Agents (PUAs) using this   extension provide as complete presence information as they can.  If   the PUA is publishing sensitive information using this extension, it   SHOULD obtain permission from the presentity.  PUAs can indicate the   explicitly supported capabilities using the <supported> element, and   the capabilities that are explicitly not supported using the   <notsupported> element.   It is not mandated that presence information be consistent with   actual service or device capabilities.  However, it is in the   presentity's best interest to avoid publishing false presence   information and provide accurate information to help minimize   unsuccessful communication invitations.  Otherwise, watchers may   conclude that communication cannot be established with the   presentity, but in reality it would be possible; or watchers may   conclude that certain communication capabilities are available, but   in reality a communication establishment attempt would fail using   those capabilities.  In any case, watchers should not expect the   presence information represented by this extension to be fully   aligned with the actual presentity's service or device capabilities.   As explained inSection 1.2, presence of this extension does not   replace the use of SIP signaling for capability negotiation.4.1.  Use of <supported> and <notsupported> Elements   PUAs should add information under <supported> and <notsupported>   elements only when they believe it may affect the decision making in   the watcher's end, i.e., information should be relevant and valuable   for the watcher.  Listing all possible information under <supported>   and <notsupported> is rarely needed.   For example, if the PUA wants to advertise a message service that   supports the MESSAGE method, it should add it under the <supported>   element in the <methods> element.  Even if the service does notLonnfors & Kiss             Standards Track                    [Page 15]

RFC 5196         User Agent Capability Presence Status    September 2008   support other methods, it is unlikely that listing all the methods   not supported under the <notsupported> element would provide any   value to the watcher.   In case of conflicting information, i.e., the same child element   appears under the <supported> and <notsupported> elements with the   same value, the watcher can safely assume that the listed capability   is supported regardless of the inclusion of the capability under the   <notsupported> element.5.  Examples   <?xml version="1.0" encoding="UTF-8"?>   <presence xmlns="urn:ietf:params:xml:ns:pidf"         xmlns:caps="urn:ietf:params:xml:ns:pidf:caps"         xmlns:mod="urn:ietf:params:xml:ns:pidf:data-model"         entity="pres:someone@example.com">     <tuple>       <status>         <basic>open</basic>       </status>       <caps:servcaps>         <caps:audio>true</caps:audio>         <caps:description xml:lang="en">            Example service         </caps:description>         <caps:description xml:lang="hu">            Pe'lda szolga'ltata's         </caps:description>         <caps:duplex>           <caps:supported>             <caps:full/>           </caps:supported>         </caps:duplex>         <caps:message>true</caps:message>         <caps:methods>           <caps:supported>             <caps:ACK/>             <caps:BYE/>             <caps:INVITE/>             <caps:MESSAGE/>           </caps:supported>         </caps:methods>         <caps:priority>           <caps:supported>             <caps:lowerthan maxvalue="10"/>           </caps:supported>Lonnfors & Kiss             Standards Track                    [Page 16]

RFC 5196         User Agent Capability Presence Status    September 2008         </caps:priority>         <caps:schemes>           <caps:supported>             <caps:s>sip</caps:s>           </caps:supported>         </caps:schemes>         <caps:video>false</caps:video>       </caps:servcaps>       <contact>sip:someone@example.com</contact>     </tuple>     <mod:device>       <caps:devcaps>         <caps:mobility>           <caps:supported>             <caps:mobile/>           </caps:supported>         </caps:mobility>       </caps:devcaps>       <mod:deviceID        >urn:uuid:d27459b7-8213-4395-aa77-ed859a3e5b3a</mod:deviceID>     </mod:device>   </presence>6.  XML Schema Definitions   This section gives the XML schema definitions for the extensions   defined in this document.  The namespace identifier for this schema   is urn:ietf:params:xml:ns:pidf:caps.<?xml version="1.0" encoding="UTF-8"?><xs:schema xmlns:tns="urn:ietf:params:xml:ns:pidf:caps"  xmlns:xs="http://www.w3.org/2001/XMLSchema"  targetNamespace="urn:ietf:params:xml:ns:pidf:caps"  elementFormDefault="qualified"  attributeFormDefault="unqualified"><!-- This import brings in the XML language     attribute xml:lang--> <xs:import namespace="http://www.w3.org/XML/1998/namespace"  schemaLocation="http://www.w3.org/2001/xml.xsd"/><!-- ROOT --> <xs:element name="servcaps" type="tns:servcapstype"/> <xs:complexType name="servcapstype">  <xs:sequence>   <xs:element name="actor" type="tns:actortype"    minOccurs="0"/>Lonnfors & Kiss             Standards Track                    [Page 17]

RFC 5196         User Agent Capability Presence Status    September 2008   <xs:element name="application" type="tns:applicationtype"    minOccurs="0"/>   <xs:element name="audio" type="tns:audiotype" minOccurs="0"/>   <xs:element name="automata" type="tns:automatatype"    minOccurs="0"/>   <xs:element name="class" type="tns:classtype"    minOccurs="0"/>   <xs:element name="control" type="tns:controltype"    minOccurs="0"/>   <xs:element name="data" type="tns:datatype"    minOccurs="0"/>   <xs:element name="description" type="tns:descriptiontype"    minOccurs="0" maxOccurs="unbounded"/>   <xs:element name="duplex" type="tns:duplextype"    minOccurs="0"/>   <xs:element name="event-packages" type="tns:event-packagestype"    minOccurs="0"/>   <xs:element name="extensions" type="tns:extensionstype"    minOccurs="0"/>   <xs:element name="isfocus" type="tns:isfocustype"    minOccurs="0"/>   <xs:element name="message" type="tns:messagetype"    minOccurs="0"/>   <xs:element name="methods" type="tns:methodstype"    minOccurs="0"/>   <xs:element name="languages" type="tns:languagestype"    minOccurs="0"/>   <xs:element name="priority" type="tns:prioritytype"    minOccurs="0"/>   <xs:element name="schemes" type="tns:schemestype"    minOccurs="0"/>   <xs:element name="text" type="tns:texttype"    minOccurs="0"/>   <xs:element name="type" type="tns:typetype"    minOccurs="0" maxOccurs="unbounded"/>   <xs:element name="video" type="tns:videotype"    minOccurs="0"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0" maxOccurs="unbounded"/>  </xs:sequence> <xs:anyAttribute namespace="##any" processContents="lax"/> </xs:complexType> <xs:element name="devcaps" type="tns:devcaps"/> <xs:complexType name="devcaps">  <xs:sequence>   <xs:element name="description" type="tns:descriptiontype"    minOccurs="0" maxOccurs="unbounded"/>Lonnfors & Kiss             Standards Track                    [Page 18]

RFC 5196         User Agent Capability Presence Status    September 2008   <xs:element name="mobility" type="tns:mobilitytype"    minOccurs="0"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0" maxOccurs="unbounded"/>  </xs:sequence> <xs:anyAttribute namespace="##any" processContents="lax"/> </xs:complexType> <!-- AUDIO --> <xs:simpleType name="audiotype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- APPLICATION --> <xs:simpleType name="applicationtype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- DATA --> <xs:simpleType name="datatype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- CONTROL --> <xs:simpleType name="controltype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- VIDEO --> <xs:simpleType name="videotype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- TEXT --> <xs:simpleType name="texttype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- MESSAGE --> <xs:simpleType name="messagetype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- TYPE --> <xs:simpleType name="typetype">  <xs:restriction base="xs:string"/> </xs:simpleType>Lonnfors & Kiss             Standards Track                    [Page 19]

RFC 5196         User Agent Capability Presence Status    September 2008 <!-- AUTOMATA --> <xs:simpleType name="automatatype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- CLASS --> <xs:complexType name="classtype">  <xs:sequence>   <xs:element name="supported" type="tns:classtypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:classtypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="classtypes">  <xs:sequence>   <xs:element name="business" type="xs:string"    minOccurs="0"/>   <xs:element name="personal" type="xs:string"    minOccurs="0"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0"    maxOccurs="unbounded"/>  </xs:sequence> </xs:complexType> <!-- DUPLEX --> <xs:complexType name="duplextype">  <xs:sequence>   <xs:element name="supported" type="tns:duplextypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:duplextypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="duplextypes">  <xs:sequence>   <xs:element name="full" type="xs:string"    minOccurs="0"/>   <xs:element name="half" type="xs:string"    minOccurs="0"/>   <xs:element name="receive-only" type="xs:string"    minOccurs="0"/>   <xs:element name="send-only" type="xs:string"    minOccurs="0"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0" maxOccurs="unbounded"/>  </xs:sequence>Lonnfors & Kiss             Standards Track                    [Page 20]

RFC 5196         User Agent Capability Presence Status    September 2008 </xs:complexType> <!-- DESCRIPTION --> <xs:complexType name="descriptiontype">  <xs:simpleContent>   <xs:extension base="xs:string">    <xs:attribute ref="xml:lang"/>   </xs:extension>  </xs:simpleContent> </xs:complexType> <!-- EVENT-PACKAGES --> <xs:complexType name="event-packagestype">  <xs:sequence>   <xs:element name="supported" type="tns:eventtypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:eventtypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="eventtypes">  <xs:sequence>   <xs:element name="conference" type="xs:string"    minOccurs="0"/>   <xs:element name="dialog" type="xs:string"    minOccurs="0"/>   <xs:element name="kpml" type="xs:string"    minOccurs="0"/>   <xs:element name="message-summary" type="xs:string"    minOccurs="0"/>   <xs:element name="poc-settings" type="xs:string"    minOccurs="0"/>   <xs:element name="presence" type="xs:string"    minOccurs="0"/>   <xs:element name="reg" type="xs:string"    minOccurs="0"/>   <xs:element name="refer" type="xs:string"    minOccurs="0"/>   <xs:element name="Siemens-RTP-Stats"    type="xs:string" minOccurs="0"/>   <xs:element name="spirits-INDPs"    type="xs:string" minOccurs="0"/>   <xs:element name="spirits-user-prof"    type="xs:string" minOccurs="0"/>   <xs:element name="winfo" type="xs:string"    minOccurs="0"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0" maxOccurs="unbounded"/>Lonnfors & Kiss             Standards Track                    [Page 21]

RFC 5196         User Agent Capability Presence Status    September 2008  </xs:sequence> </xs:complexType> <!-- PRIORITY --> <xs:complexType name="prioritytype">  <xs:sequence>   <xs:element name="supported" type="tns:prioritytypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:prioritytypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="prioritytypes">  <xs:sequence>   <xs:element name="equals" type="tns:equalstype"    minOccurs="0" maxOccurs="unbounded"/>   <xs:element name="higherhan" type="tns:higherthantype"    minOccurs="0" maxOccurs="unbounded"/>   <xs:element name="lowerthan" type="tns:lowerthantype"    minOccurs="0" maxOccurs="unbounded"/>   <xs:element name="range" type="tns:rangetype"    minOccurs="0" maxOccurs="unbounded"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0" maxOccurs="unbounded"/>  </xs:sequence> </xs:complexType> <xs:complexType name="lowerthantype">  <xs:attribute name="maxvalue" type="xs:integer"   use="required"/> </xs:complexType> <xs:complexType name="higherthantype">  <xs:attribute name="minvalue" type="xs:integer"   use="required"/> </xs:complexType> <xs:complexType name="equalstype">  <xs:attribute name="value" type="xs:integer"   use="required"/> </xs:complexType> <xs:complexType name="rangetype">  <xs:attribute name="minvalue" type="xs:integer"   use="required"/>  <xs:attribute name="maxvalue" type="xs:integer"   use="required"/> </xs:complexType> <!-- METHODS --> <xs:complexType name="methodstype">  <xs:sequence>Lonnfors & Kiss             Standards Track                    [Page 22]

RFC 5196         User Agent Capability Presence Status    September 2008   <xs:element name="supported" type="tns:methodtypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:methodtypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="methodtypes">  <xs:sequence>   <xs:element name="ACK" type="xs:string" minOccurs="0"/>   <xs:element name="BYE" type="xs:string" minOccurs="0"/>   <xs:element name="CANCEL" type="xs:string" minOccurs="0"/>   <xs:element name="INFO" type="xs:string" minOccurs="0"/>   <xs:element name="INVITE" type="xs:string" minOccurs="0"/>   <xs:element name="MESSAGE" type="xs:string" minOccurs="0"/>   <xs:element name="NOTIFY" type="xs:string" minOccurs="0"/>   <xs:element name="OPTIONS" type="xs:string" minOccurs="0"/>   <xs:element name="PRACK" type="xs:string" minOccurs="0"/>   <xs:element name="PUBLISH" type="xs:string" minOccurs="0"/>   <xs:element name="REFER" type="xs:string" minOccurs="0"/>   <xs:element name="REGISTER" type="xs:string" minOccurs="0"/>   <xs:element name="SUBSCRIBE" type="xs:string" minOccurs="0"/>   <xs:element name="UPDATE" type="xs:string" minOccurs="0"/>   <xs:any namespace="##other" processContents="lax" minOccurs="0"    maxOccurs="unbounded"/>  </xs:sequence> </xs:complexType> <!-- EXTENSIONS --> <xs:complexType name="extensionstype">  <xs:sequence>   <xs:element name="supported" type="tns:extensiontypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:extensiontypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="extensiontypes">  <xs:sequence>   <xs:element name="rel100" type="xs:string" minOccurs="0"/>   <xs:element name="early-session" type="xs:string" minOccurs="0"/>   <xs:element name="eventlist" type="xs:string" minOccurs="0"/>   <xs:element name="from-change" type="xs:string" minOccurs="0"/>   <xs:element name="gruu" type="xs:string" minOccurs="0"/>   <xs:element name="hist-info" type="xs:string" minOccurs="0"/>   <xs:element name="join" type="xs:string" minOccurs="0"/>   <xs:element name="norefersub" type="xs:string" minOccurs="0"/>   <xs:element name="path" type="xs:string" minOccurs="0"/>   <xs:element name="precondition" type="xs:string" minOccurs="0"/>Lonnfors & Kiss             Standards Track                    [Page 23]

RFC 5196         User Agent Capability Presence Status    September 2008   <xs:element name="pref" type="xs:string" minOccurs="0"/>   <xs:element name="privacy" type="xs:string" minOccurs="0"/>   <xs:element name="recipient-list-invite" type="xs:string"    minOccurs="0"/>   <xs:element name="recipient-list-subscribe" type="xs:string"    minOccurs="0"/>   <xs:element name="replaces" type="xs:string" minOccurs="0"/>   <xs:element name="resource-priority" type="xs:string" minOccurs="0"/>   <xs:element name="sdp-anat" type="xs:string" minOccurs="0"/>   <xs:element name="sec-agree" type="xs:string" minOccurs="0"/>   <xs:element name="tdialog" type="xs:string" minOccurs="0"/>   <xs:element name="timer" type="xs:string" minOccurs="0"/>   <xs:any namespace="##other" processContents="lax"    minOccurs="0" maxOccurs="unbounded"/>  </xs:sequence> </xs:complexType> <!-- SCHEMES --> <xs:complexType name="schemestype">  <xs:sequence>   <xs:element name="supported" minOccurs="0">    <xs:complexType>     <xs:sequence>      <xs:element name="s" type="xs:string" maxOccurs="unbounded"/>     </xs:sequence>    </xs:complexType>   </xs:element>   <xs:element name="notsupported" minOccurs="0">    <xs:complexType>     <xs:sequence>      <xs:element name="s" type="xs:string" maxOccurs="unbounded"/>     </xs:sequence>    </xs:complexType>   </xs:element>  </xs:sequence> </xs:complexType> <!-- ACTOR --> <xs:complexType name="actortype">  <xs:sequence>   <xs:element name="supported" type="tns:actortypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:actortypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="actortypes">  <xs:sequence>Lonnfors & Kiss             Standards Track                    [Page 24]

RFC 5196         User Agent Capability Presence Status    September 2008   <xs:element name="attendant" type="xs:string" minOccurs="0"/>   <xs:element name="information" type="xs:string" minOccurs="0"/>   <xs:element name="msg-taker" type="xs:string" minOccurs="0"/>   <xs:element name="principal" type="xs:string" minOccurs="0"/>   <xs:any namespace="##other" processContents="lax" minOccurs="0"    maxOccurs="unbounded"/>  </xs:sequence> </xs:complexType> <!-- ISFOCUS --> <xs:simpleType name="isfocustype">  <xs:restriction base="xs:boolean"/> </xs:simpleType> <!-- LANGUAGES --> <xs:complexType name="languagestype">  <xs:sequence>   <xs:element name="supported" minOccurs="0">    <xs:complexType>     <xs:sequence>      <xs:element name="l" type="xs:string" maxOccurs="unbounded"/>     </xs:sequence>    </xs:complexType>   </xs:element>   <xs:element name="notsupported" minOccurs="0">    <xs:complexType>     <xs:sequence>      <xs:element name="l" type="xs:string" maxOccurs="unbounded"/>     </xs:sequence>    </xs:complexType>   </xs:element>  </xs:sequence> </xs:complexType> <!-- MOBILITY --> <xs:complexType name="mobilitytype">  <xs:sequence>   <xs:element name="supported" type="tns:mobilitytypes"    minOccurs="0"/>   <xs:element name="notsupported" type="tns:mobilitytypes"    minOccurs="0"/>  </xs:sequence> </xs:complexType> <xs:complexType name="mobilitytypes">  <xs:sequence>   <xs:element name="fixed" type="xs:string"    minOccurs="0"/>   <xs:element name="mobile" type="xs:string"Lonnfors & Kiss             Standards Track                    [Page 25]

RFC 5196         User Agent Capability Presence Status    September 2008    minOccurs="0"/>   <xs:any namespace="##other" processContents="lax" minOccurs="0"    maxOccurs="unbounded"/>  </xs:sequence> </xs:complexType></xs:schema>7.  IANA Considerations   IANA has registered one new XML namespace URN and one schema as   defined in [RFC3688].7.1.  URN Sub-Namespace Registration for      'urn:ietf:params:xml:ns:pidf:caps'   URI:   urn:ietf:params:xml:ns:pidf:caps   Description:   This is the XML namespace for XML elements defined byRFC 5196 to   describe service and device capabilities in application/pidf+xml   content type.   Registrant Contact:   IETF, SIMPLE working group, <simple@ietf.org>   Mikko Lonnfors, <mikko.lonnfors@nokia.com>   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>Namespace for PIDF user agent capability               extension</title>   </head>   <body>       <h1>Namespace for PIDF service capability extension</h1>       <h2>urn:ietf:params:xml:ns:pidf:caps</h2>       <p>         See <a href="http://www.rfc-editor.org/rfc/rfc5196.txt">RFC5196</a>.       </p>    </body>Lonnfors & Kiss             Standards Track                    [Page 26]

RFC 5196         User Agent Capability Presence Status    September 2008    </html>   END7.2.  Schema Registration for Schema      'urn:ietf:params:xml:schema:pidf:caps'   URI:   urn:ietf:params:xml:schema:pidf:caps   Registrant Contact:   IESG   XML:   SeeSection 68.  Security Considerations   All security considerations specified in [RFC3859] and [RFC3863]   apply to this document.  Compared to PIDF [RFC3863], this presence   document format may reveal additional information about user's   service and device capabilities.  Thus, the PUA SHOULD always obtain   permission from the presentity when publishing sensitive information   using this extension.9.  Acknowledgments   Authors of this document would like to thank the following people for   their contributions and valuable comments: Paul Kyzivat, Jonathan   Rosenberg, Markus Isomaki, Eva Leppanen, Miguel Garcia, Jari   Urpalainen, and Hisham Khartabil.10.  References10.1.  Normative References   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail              Extensions (MIME) part one: Format of Internet Message              Bodies",RFC 2045, November 1996.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and              Languages",BCP 18,RFC 2277, January 1998.   [RFC2913]  Klyne, G., "MIME Content Types in Media Feature              Expressions",RFC 2913, September 2000.Lonnfors & Kiss             Standards Track                    [Page 27]

RFC 5196         User Agent Capability Presence Status    September 2008   [RFC3688]  Mealling, M., "The IETF XML Registry",BCP 81,RFC 3688,              January 2004.   [RFC3840]  Schulzrinne, H., Rosenberg, J., and P. Kyzivat,              "Indicating User Agent Capabilities in the Session              Initiation Protocol (SIP)",RFC 3840, August 2004.   [RFC3859]  Peterson, J., "Common Profile for Presence (CPP)",RFC 3859, August 2004.   [RFC3863]  Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr,              W., and J. Peterson, "Presence Information Data Format              (PIDF)",RFC 3863, August 2004.   [RFC4479]  Rosenberg, J., "A Data Model for Presence",RFC 4479,              July 2006.   [RFC4646]  Phillips, A. and M. Davis, "Tags for Identifying              Languages",BCP 47,RFC 4646, September 2006.10.2.  Informative References   [RFC2648]  Moats, R., "A URN namespace for IETF documents",RFC 2648,              August 1999.   [RFC2778]  Day, M., Rosenberg, J., and H. Sugano, "A Model for              Presence and Instant Messaging",RFC 2778, February 2000.   [RFC3860]  Peterson, J., "Common Profile for Instant Messaging              (CPIM)",RFC 3860, August 2004.   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session              Description Protocol",RFC 4566, July 2006.   [RFC4569]  Camarillo, G., "Internet Assigned Numbers Authority (IANA)              Registration of the Message Media Feature Tag",RFC 4569,              July 2006.Lonnfors & Kiss             Standards Track                    [Page 28]

RFC 5196         User Agent Capability Presence Status    September 2008Authors' Addresses   Mikko Lonnfors   Nokia   P.O. Box 321   Helsinki   Finland   Phone: +358 71 8008000   EMail: mikko.lonnfors@nokia.com   Krisztian Kiss   Nokia   313 Fairchild Dr   Mountain View, CA 94043   US   Phone: +1 650 391 5969   EMail: krisztian.kiss@nokia.comLonnfors & Kiss             Standards Track                    [Page 29]

RFC 5196         User Agent Capability Presence Status    September 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   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, THE IETF TRUST 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.Lonnfors & Kiss             Standards Track                    [Page 30]

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