Network Working Group H. Schulzrinne
Request for Comments: 4480 Columbia U.
Category: Standards Track V. Gurbani
 Lucent
 P. Kyzivat
 J. Rosenberg
 Cisco
 July 2006
 RPID: Rich Presence Extensions to the
 Presence 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.
Table of Contents
 1. Introduction ....................................................2
 2. Terminology and Conventions .....................................4
 3. RPID Elements ...................................................4
 3.1. Overview ...................................................4
 3.2. Activities Element .........................................7
 3.3. Class Element .............................................10
 3.4. Device Identifier .........................................10
 3.5. Mood Element ..............................................10
 3.6. Place-is Element ..........................................12
 3.7. Place-type Element ........................................13
 3.8. Privacy Element ...........................................14
 3.9. Relationship Element ......................................15
 3.10. Service Class ............................................15
 3.11. Sphere Element ...........................................16
 3.12. Status-Icon Element ......................................16
 3.13. Time Offset ..............................................17
 3.14. User-Input Element .......................................17
 4. Example ........................................................18
 5. XML Schema Definitions .........................................20
 5.1. urn:ietf:params:xml:ns:pidf:rpid ..........................20
 6. Extending RPID .................................................30
 7. IANA Considerations ............................................31
 7.1. 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 ............................32
 9. Security Considerations ........................................32
 10. References ....................................................33
 10.1. Normative References .....................................33
 10.2. Informative References ...................................34
 Appendix A. Acknowledgements .....................................35
1. 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".
 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 in RFC 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, and
 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 in BCP 14, RFC 2119 [1].
3. RPID Elements
3.1. 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.
 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 respective
 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.
 Enumerations can be extended by elements from other namespaces, as
 described in Section 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 as
 Section 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 away
 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.
 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 in Section 3.1.
 Example:
 <activities>
 <note>Enjoying the morning paper</note>
 <vacation/>
 <breakfast/>
 <other>reading</other>
 </activities>
3.3. 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 in Section 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 in Section 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 in Section 3.1.
 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 remorseful
 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.
 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 in Section 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 in RFC 4589 [12].
 This list can be augmented by free-text values or additional IANA-
 registered values as described in RFC 4589.
 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 in Section 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 in Section 3.1.
 Example:
 <privacy>
 <text/>
 <audio/>
 </privacy>
3.9. 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.
 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 in Section 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 of
 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 input
 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 an
 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 id="bs35r9">
 <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年10月27日T16:49:29Z</timestamp>
 </tuple>
 <tuple id="ty4658">
 <status>
 <basic>open</basic>
 </status>
 <rpid:relationship><rpid:assistant/></rpid:relationship>
 <contact priority="1.0">mailto:secretary@example.com</contact>
 </tuple>
 <tuple id="eg92n8">
 <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 id="pc147">
 <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>
 <dm:note>PC</dm:note>
 </dm:device>
 <dm:person id="p1">
 <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年05月30日T16:09:44+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"
 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" />
 <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>
 </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" />
 <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" />
 <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"/>
 <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>
 <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>
 <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>
 </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>
 <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.
 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 Considerations
7.1. 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 by
 RFC 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>
 END
7.2. 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: See Section 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 in
 Section 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.
 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. References
10.1. 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)", RFC
 3863, 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.
10.2. 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.
Appendix 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.
Authors' 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.com
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