One document matched: draft-ietf-xmpp-address-00.xml
<?xml version="1.0"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc compact="yes"?>
<?rfc strict="yes"?>
<?rfc symrefs="yes"?>
<?rfc toc="yes"?>
<?rfc tocdepth="4"?>
<rfc category="std" docName="draft-ietf-xmpp-address-00" ipr="trust200902">
<front>
<title abbrev="XMPP Address Format">Extensible Messaging and Presence Protocol (XMPP): Address Format</title>
<author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
<organization>Cisco</organization>
<address>
<email>psaintan@cisco.com</email>
</address>
</author>
<date year="2010" month="April" day="7"/>
<area>Applications</area>
<keyword>Extensible Messaging and Presence Protocol</keyword>
<keyword>XMPP</keyword>
<keyword>Jabber</keyword>
<keyword>Messaging</keyword>
<keyword>Instant Messaging</keyword>
<keyword>Presence</keyword>
<keyword>Extensible Markup Language</keyword>
<keyword>XML</keyword>
<abstract>
<t>This document defines the format for addresses used in the Extensible Messaging and Presence Protocol (XMPP), including support for non-ASCII characters.</t>
</abstract>
</front>
<middle>
<section title="Introduction" anchor="intro">
<t>The Extensible Messaging and Presence Protocol <xref target='XMPP'/> is an application profile of the Extensible Markup Language <xref target="XML"/> for streaming XML data in close to real time between any two or more network-aware entities. The address format for such entities was originally developed in the Jabber open-source community in 1999 (thus for historical reasons the native address of an XMPP entity is called a Jabber Identifier or JID). In essence, a JID contains up to three parts, in the arrangement <localpart@domainpart/resourcepart> (where the localpart and resourcepart are both discretionary and each part can contain nearly any Unicode code point, encoded according to <xref target='UTF-8'/>). The JID format was first described by <xref target='XEP-0029'/> in 2002-2003, then defined canonically by <xref target='RFC3920'/> in 2004. As defined in RFC 3920, the XMPP address format re-uses the "stringprep" technology for preparation of non-ASCII characters <xref target='STRINGPREP'/>, including the Nameprep profile for internationalized domain names as specified in <xref target='NAMEPREP'/> and <xref target='IDNA2003'/> as well as two XMPP-specific profiles for the localpart and resourcepart. Since the publication of RFC 3920, IDNA2003 has been superseded by IDNA2008, and other protocols that use stringprep (including XMPP) have begun to migrate away from that technology. Because work on improved handling of internationalized addresses is currently in progress, specifying the XMPP address format in the revisions to RFC 3920 would unacceptably delay the revision process. Therefore, this specification provides documentation of the XMPP address format from RFC 3920, with the intent that it can be superseded once work on a new approach to internationalization is complete.</t>
</section>
<section title="Addresses" anchor="addressing">
<section title="Overview" anchor="addressing-overview">
<t><iref item='Entity'/>An ENTITY is anything that is network-addressable and that can communicate using XMPP. <iref item='Jabber Identifier'/>For historical reasons, the native address of an XMPP entity is called a JABBER IDENTIFIER or JID. A valid JID contains a set of ordered elements formed of an XMPP localpart, domainpart, and resourcepart.</t>
<t>The syntax for a JID is defined as follows using the Augmented Backus-Naur Form as specified in <xref target="ABNF"/>.</t>
<figure>
<artwork><![CDATA[
jid = [ localpart "@" ] domain [ "/" resource ]
localpart = 1*(nodepoint)
; a "nodepoint" is a UTF-8 encoded Unicode code
; point that satisfies the Nodeprep profile of
; stringprep
domain = fqdn / address-literal
fqdn = *(ldhlabel ".") toplabel
ldhlabel = letdig [*61(ldh) letdig]
toplabel = ALPHA *61(ldh) letdig
letdig = ALPHA / DIGIT
ldh = ALPHA / DIGIT / "-"
address-literal = IPv4address / IPv6address
; the "IPv4address" and "IPv6address" rules are
; defined in RFC 3986
resource = 1*(resourcepoint)
; a "resourcepoint" is a UTF-8 encoded Unicode
; code point that satisfies the Resourceprep
; profile of stringprep
]]></artwork>
</figure>
<t>All JIDs are based on the foregoing structure. One common use of this structure is to identify a messaging and presence account, the server that hosts the account, and a connected resource (e.g., a specific device) in the form of <localpart@domain/resource>. However, localparts other than clients are possible; for example, a specific chat room offered by a multi-user conference service (see <xref target='XEP-0045'/>) could be addressed as <room@service> (where "room" is the name of the chat room and "service" is the hostname of the multi-user conference service) and a specific occupant of such a room could be addressed as <room@service/nick> (where "nick" is the occupant's room nickname). Many other JID types are possible (e.g., <domain/resource> could be a server-side script or service).</t>
<t>Each allowable portion of a JID (localpart, domainpart, and resourcepart) MUST NOT be more than 1023 bytes in length, resulting in a maximum total size (including the '@' and '/' separators) of 3071 bytes.</t>
<t><list style='empty'><t>Note: While the format of a JID is consistent with <xref target="URI"/>, an entity's address on an XMPP network MUST be represented as a JID (without a URI scheme) and not a <xref target="URI"/> or <xref target="IRI"/> as specified in <xref target="XMPP-URI"/>; the latter specification is provided only for identification and interaction outside the context of the XMPP wire protocol itself.</t></list></t>
</section>
<section title="Domainpart" anchor="addressing-domain">
<t><iref item='Domainpart'/>The DOMAINPART of a JID is that portion after the '@' character (if any) and before the '/' character (if any); it is the primary identifier and is the only REQUIRED element of a JID (a mere domainpart is a valid JID). Typically a domainpart identifies the "home" server to which clients connect for XML routing and data management functionality. However, it is not necessary for an XMPP domainpart to identify an entity that provides core XMPP server functionality (e.g., a domainpart can identity an entity such as a multi-user conference service, a publish-subscribe service, or a user directory).</t>
<t><list style='empty'><t>Note: A single server can service multiple domainparts, i.e., multiple local domains; this is typically referred to as virtual hosting.</t></list></t>
<t>The domainpart for every server or service that will communicate over a network SHOULD be a fully qualified domain name (see <xref target='DNS'/>); while the domainpart MAY be either an Internet Protocol (IPv4 or IPv6) address or a text label that is resolvable on a local network (commonly called an "unqualified hostname"), it is possible that domainparts that are IP addresses will not be acceptable to other services for the sake of interdomain communication. Furthermore, domainparts that are unqualified hostnames MUST NOT be used on public networks but MAY be used on private networks.</t>
<t><list style='empty'><t>Note: If the domainpart includes a final character considered to be a label separator (dot) by <xref target='IDNA2003'/> or <xref target='DNS'/>, this character MUST be stripped from the domainpart before the JID of which it is a part is used for the purpose of routing an XML stanza, comparing against another JID, or constructing an <xref target='XMPP-URI'/>; in particular, the character MUST be stripped before any other canonicalization steps are taken, such as application of the <xref target='NAMEPREP'/> profile of <xref target='STRINGPREP'/> or completion of the ToASCII operation as described in <xref target='IDNA2003'/>.</t></list></t>
<t>A domainpart MUST be an "internationalized domain name" as defined in <xref target='IDNA2003'/>, that is, "a domain name in which every label is an internationalized label". When preparing a text label (consisting of a sequence of Unicode code points) for representation as an internationalized label in the process of constructing an XMPP domainpart or comparing two XMPP domainparts, an application MUST ensure that for each text label it is possible to apply without failing the ToASCII operation specified in <xref target='IDNA2003'/> with the UseSTD3ASCIIRules flag set (thus forbidding ASCII code points other than letters, digits, and hyphens). If the ToASCII operation can be applied without failing, then the label is an internationalized label. An internationalized domain name (and therefore an XMPP domainpart) is constructed from its constituent internationalized labels by following the rules specified in <xref target='IDNA2003'/>.</t>
<t><list style='empty'><t>Note: The ToASCII operation includes application of the <xref target='NAMEPREP'/> profile of <xref target='STRINGPREP'/> and encoding using the algorithm specified in <xref target='PUNYCODE'/>; for details, see <xref target='IDNA2003'/>. Although the output of the ToASCII operation is not used in XMPP, it MUST be possible to apply that operation without failing.</t></list></t>
<t>In the terms of IDNA2008 <xref target='IDNA-DEFS'/>, the domainpart of a JID is a "domain name slot".</t>
</section>
<section title='Localpart' anchor='addressing-localpart'>
<t><iref item='Localpart'/>The LOCALPART of a JID is an optional identifier placed before the domainpart and separated from the latter by the '@' character. Typically a localpart uniquely identifies the entity requesting and using network access provided by a server (i.e., a local account), although it can also represent other kinds of entities (e.g., a chat room associated with a multi-user conference service). The entity represented by an XMPP localpart is addressed within the context of a specific domain.</t>
<t>A localpart MUST NOT be zero bytes in length and, as for all portions of a JID, MUST NOT be more than 1023 bytes in length.</t>
<t>A localpart MUST be formatted such that the Nodeprep profile of <xref target="STRINGPREP"/> can be applied without failing (see <xref target="nodeprep"/>). Before comparing two localparts, an application MUST first ensure that the Nodeprep profile has been applied to each identifier (the profile need not be applied each time a comparison is made, as long as it has been applied before comparison).</t>
</section>
<section title="Resourcepart" anchor="addressing-resource">
<t><iref item='Resourcepart'/>The resourcepart of a JID is an optional identifier placed after the domainpart and separated from the latter by the '/' character. A resourcepart can modify either a <localpart@domain> address or a mere <domain> address. Typically a resourcepart uniquely identifies a specific connection (e.g., a device or location) or object (e.g., a participant in a multi-user conference room) belonging to the entity associated with an XMPP localpart at a local domain.</t>
<t><iref item='Bare JID'/>When an XMPP address does not include a resourcepart (i.e., when it is of the form <domain> or <localpart@domain>), it is referred to as a BARE JID. <iref item='Full JID'/>When an XMPP address includes a resourcepart (i.e., when it is of the form <domain/resource> or <localpart@domain/resource>), is referred to as a FULL JID.</t>
<t>A resourcepart MUST NOT be zero bytes in length and, as for all portions of a JID, MUST NOT be more than 1023 bytes in length.</t>
<t>A resourcepart MUST be formatted such that the Resourceprep profile of <xref target="STRINGPREP"/> can be applied without failing (see <xref target="resourceprep"/>). Before comparing two resourceparts, an application MUST first ensure that the Resourceprep profile has been applied to each identifier (the profile need not be applied each time a comparison is made, as long as it has been applied before comparison).</t>
<t><list style='empty'><t>Note: For historical reasons, the term "resource identifier" is often used in XMPP to refer to the optional portion of an XMPP address that follows the domainpart and the "/" separator character; to help prevent confusion between an XMPP "resource identifier" and the meanings of "resource" and "identifier" provided in Section 1.1 of <xref target="URI"/>, this specification typically uses the term "resourcepart" instead of "resource identifier" (as in RFC 3920).</t></list></t>
<t>XMPP entities SHOULD consider resourceparts to be opaque strings and SHOULD NOT impute meaning to any given resourcepart. In particular, the use of the '/' character as a separator between the domainpart and the resourcepart does not imply that XMPP addresses are hierarchical in the way that, say, HTTP addresses are hierarchical; thus for example an XMPP address of the form <localpart@domain/foo/bar> does not identify a resource "bar" that exists below a resource "foo" in a hierarchy of resources associated with the entity "localpart@domain".</t>
</section>
</section>
<section title="Internationalization Considerations" anchor="i18n">
<t>An XMPP server MUST support and enforce <xref target="IDNA2003"/> for domainparts, the <xref target='nodeprep'>Nodeprep</xref> profile of <xref target="STRINGPREP"/> for localparts, and the <xref target='resourceprep'>Resourceprep</xref> profile of <xref target="STRINGPREP"/> for resourceparts; this enables XMPP addresses to include a wide variety of Unicode characters outside the US-ASCII range.</t>
</section>
<section title="Security Considerations" anchor="security">
<section title="Stringprep Profiles" anchor="security-stringprep">
<t>XMPP makes use of the <xref target="NAMEPREP"/> profile of <xref target="STRINGPREP"/> for processing of domainparts; for security considerations related to Nameprep, refer to the appropriate section of <xref target="NAMEPREP"/>.</t>
<t>In addition, XMPP defines two profiles of <xref target="STRINGPREP"/>: <xref target="nodeprep">Nodeprep</xref> for localparts and <xref target="resourceprep">Resourceprep</xref> for resourceparts.</t>
<t>The Unicode and ISO/IEC 10646 repertoires have many characters that look similar. In many cases, users of security protocols might perform visual matching, such as when comparing the names of trusted third parties. Because it is impossible to map similar-looking characters without a great deal of context (such as knowing the fonts used), stringprep does nothing to map similar-looking characters together, nor to prohibit some characters because they look like others.</t>
<t>A localpart can be employed as one part of an entity's address in XMPP. One common usage is as the username of an instant messaging user; another is as the name of a multi-user conference room; and many other kinds of entities could use localparts as part of their addresses. The security of such services could be compromised based on different interpretations of the internationalized localpart; for example, a user entering a single internationalized localpart could access another user's account information, or a user could gain access to a hidden or otherwise restricted chat room or service.</t>
<t>A resourcepart can be employed as one part of an entity's address in XMPP. One common usage is as the name for an instant messaging user's connected resource; another is as the nickname of a user in a multi-user conference room; and many other kinds of entities could use resourceparts as part of their addresses. The security of such services could be compromised based on different interpretations of the internationalized resourcepart; for example, a user could attempt to initiate multiple connections with the same name, or a user could send a message to someone other than the intended recipient in a multi-user conference room.</t>
</section>
<section title="Address Spoofing" anchor="security-spoofing">
<t>As discussed in <xref target='XEP-0165'/>, there are two forms of address spoofing: forging and mimicking.</t>
<section title="Address Forging" anchor="security-forging">
<t>In the context of XMPP technologies, address forging occurs when an entity is able to generate an XML stanza whose 'from' address does not correspond to the account credentials with which the entity authenticated onto the network (or an authorization identity provided during SASL negotiation). For example, address forging occurs if an entity that authenticated as "juliet@im.example.com" is able to send XML stanzas from "nurse@im.example.com" or "romeo@example.net".</t>
<t>Address forging is difficult in XMPP systems, given the requirement for sending servers to stamp 'from' addresses and for receiving servers to verify sending domains via server-to-server authentication. However, address forging is not impossible, since a rogue server could forge JIDs at the sending domain by ignoring the stamping requirement. A rogue server could even forge JIDs at other domains by means of a DNS poisoning attack if <xref target='DNSSEC'/> is not used. This specification does not define methods for discovering or counteracting such rogue servers.</t>
<t>Note: An entity outside the security perimeter of a particular server cannot reliably distinguish between bare JIDs of the form <localpart@domain> at that server, since the server could forge any such JID; therefore only the domainpart can be authenticated or authorized with any level of assurance.</t>
</section>
<section title="Address Mimicking" anchor="security-mimicking">
<t>Address mimicking occus when an entity provides legitimate authentication credentials for and sends XML stanzas from an account whose JID appears to a human user to be the same as another JID. For example, in some XMPP clients the address "paypa1@example.org" (spelled with the number one as the final character of the localpart) might appear to be the same as "paypal@example.org (spelled with the lower-case version of the letter "L"), especially on casual visual inspection; this phenomenon is sometimes called "typejacking". A more sophisticated example of address mimicking might involve the use of characters from outside the US-ASCII range, such as the Cherokee characters U+13DA U+13A2 U+13B5 U+13AC U+13A2 U+13AC U+13D2 instead of the US-ASCII characters "STPETER".</t>
<t>In some examples of address mimicking, it is unlikely that the average user could tell the difference between the real JID and the fake JID. (Naturally, there is no way to distinguish with full certainty which is the fake JID and which is the real JID; in some communication contexts, the JID with Cherokee characters might be the real JID and the JID with US-ASCII characters might thus appear to be the fake JID.) Because JIDs can contain almost any Unicode character, it can be relatively easy to mimic some JIDs in XMPP systems. The possibility of address mimicking introduces security vulnerabilities of the kind that have also plagued the World Wide Web, specifically the phenomenon known as phishing.</t>
<t>Mimicked addresses that involve characters from only one character set or from the character set typically employed by a particular user are not easy to combat (e.g., the simple typejacking attack previously described, which relies on a surface similarity between the characters "1" and "l" in some presentations). However, mimicked addresses that involve characters from more than one character set, or from a character set not typically employed by a particular user, can be mitigated somewhat through intelligent presentation. In particular, every human user of an XMPP technology presumably has a preferred language (or, in some cases, a small set of preferred languages), which an XMPP application SHOULD gather either explicitly from the user or implicitly via the operating system of the user's device. Furthermore, every language has a range (or a small set of ranges) of characters normally used to represent that language in textual form. Therefore, an XMPP application SHOULD warn the user when presenting a JID that uses characters outside the normal range of the user's preferred language(s). This recommendation is not intended to discourage communication across language communities; instead, it recognizes the existence of such language communities and encourages due caution when presenting unfamiliar character sets to human users.</t>
<t>For more detailed recommendations regarding prevention of address mimicking in XMPP systems, refer to <xref target='XEP-0165'/>.</t>
</section>
</section>
</section>
<section title="IANA Considerations" anchor="iana">
<t>The following sections update the registrations provided in <xref target='RFC3920'/>.</t>
<section title='Nodeprep Profile of Stringprep' anchor="iana-nodeprep">
<t>The Nodeprep profile of stringprep is defined under <xref target="nodeprep">Nodeprep</xref>. The IANA has registered Nodeprep in the stringprep profile registry.</t>
<t>Name of this profile:</t>
<t><list style='hanging'>
<t>Nodeprep</t>
</list></t>
<t>RFC in which the profile is defined:</t>
<t><list style='hanging'>
<t>&rfc.number;</t>
</list></t>
<t>Indicator whether or not this is the newest version of the profile:</t>
<t><list style='hanging'>
<t>This is the first version of Nodeprep</t>
</list></t>
</section>
<section title='Resourceprep Profile of Stringprep' anchor="iana-resourceprep">
<t>The Resourceprep profile of stringprep is defined under <xref target="resourceprep">Resourceprep</xref>. The IANA has registered Resourceprep in the stringprep profile registry.</t>
<t>Name of this profile:</t>
<t><list style='hanging'>
<t>Resourceprep</t>
</list></t>
<t>RFC in which the profile is defined:</t>
<t><list style='hanging'>
<t>&rfc.number;</t>
</list></t>
<t>Indicator whether or not this is the newest version of the profile:</t>
<t><list style='hanging'>
<t>This is the first version of Resourceprep</t>
</list></t>
</section>
</section>
<section title="Conformance Requirements" anchor="conformance">
<t>This section describes a protocol feature set that summarizes the conformance requirements of this specification. This feature set is appropriate for use in software certification, interoperability testing, and implementation reports. For each feature, this section provides the following information:</t>
<t>
<list style='symbols'>
<t>A human-readable name</t>
<t>An informational description</t>
<t>A reference to the particular section of this document that normatively defines the feature</t>
<t>Whether the feature applies to the Client role, the Server role, or both (where "N/A" signifies that the feature is not applicable to the specified role)</t>
<t>Whether the feature MUST or SHOULD be implemented, where the capitalized terms are to be understood as described in <xref target='TERMS'/></t>
</list>
</t>
<t>Note: The feature set specified here attempts to adhere to the concepts and formats proposed by Larry Masinter within the IETF's NEWTRK Working Group in 2005, as captured in <xref target='INTEROP'/>. Although this feature set is more detailed than called for by <xref target="REPORTS"/>, it provides a suitable basis for the generation of implementation reports to be submitted in support of advancing this specification from Proposed Standard to Draft Standard in accordance with <xref target="PROCESS"/>.</t>
<t>
<list style='hanging'>
<t hangText="Feature:">address-domain-length</t>
<t hangText="Description:">Ensure that the domainpart of an XMPP address is limited to 1023 bytes in length.</t>
<t hangText="Section:"><xref target='addressing-domain'/></t>
<t hangText="Roles:">Both MUST.</t>
</list>
</t>
<t>
<list style='hanging'>
<t hangText="Feature:">address-domain-prep</t>
<t hangText="Description:">Ensure that the domainpart of an XMPP address conforms to the Nameprep profile of Stringprep.</t>
<t hangText="Section:"><xref target='addressing-domain'/></t>
<t hangText="Roles:">Client SHOULD, Server MUST.</t>
</list>
</t>
<t>
<list style='hanging'>
<t hangText="Feature:">address-localpart-length</t>
<t hangText="Description:">Ensure that the localpart of an XMPP address is limited to 1023 bytes in length.</t>
<t hangText="Section:"><xref target='addressing-localpart'/></t>
<t hangText="Roles:">Both MUST.</t>
</list>
</t>
<t>
<list style='hanging'>
<t hangText="Feature:">address-localpart-prep</t>
<t hangText="Description:">Ensure that the localpart of an XMPP address conforms to the Nodeprep profile of Stringprep.</t>
<t hangText="Section:"><xref target='addressing-localpart'/></t>
<t hangText="Roles:">Client SHOULD, Server MUST.</t>
</list>
</t>
<t>
<list style='hanging'>
<t hangText="Feature:">address-resource-length</t>
<t hangText="Description:">Ensure that the resourcepart of an XMPP address is limited to 1023 bytes in length.</t>
<t hangText="Section:"><xref target='addressing-resource'/></t>
<t hangText="Roles:">Both MUST.</t>
</list>
</t>
<t>
<list style='hanging'>
<t hangText="Feature:">address-resource-prep</t>
<t hangText="Description:">Ensure that the resourcepart of an XMPP address conforms to the Resourceprep profile of Stringprep.</t>
<t hangText="Section:"><xref target='addressing-domain'/></t>
<t hangText="Roles:">Client SHOULD, Server MUST.</t>
</list>
</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor='ABNF'>
<front>
<title>Augmented BNF for Syntax Specifications: ABNF</title>
<author initials='D.' surname='Crocker' fullname='D. Crocker'>
<organization /></author>
<author initials='P.' surname='Overell' fullname='P. Overell'>
<organization /></author>
<date year='2008' month='January' />
<abstract>
<t>Internet technical specifications often need to define a formal syntax. Over the years, a modified version of Backus-Naur Form (BNF), called Augmented BNF (ABNF), has been popular among many Internet specifications. The current specification documents ABNF. It balances compactness and simplicity with reasonable representational power. The differences between standard BNF and ABNF involve naming rules, repetition, alternatives, order-independence, and value ranges. This specification also supplies additional rule definitions and encoding for a core lexical analyzer of the type common to several Internet specifications. [STANDARDS TRACK]</t></abstract></front>
<seriesInfo name='STD' value='68' />
<seriesInfo name='RFC' value='5234' />
<format type='TXT' octets='26359' target='ftp://ftp.isi.edu/in-notes/rfc5234.txt' />
</reference>
<reference anchor='IDNA2003'>
<front>
<title>Internationalizing Domain Names in Applications (IDNA)</title>
<author initials='P.' surname='Faltstrom' fullname='P. Faltstrom'>
<organization /></author>
<author initials='P.' surname='Hoffman' fullname='P. Hoffman'>
<organization /></author>
<author initials='A.' surname='Costello' fullname='A. Costello'>
<organization /></author>
<date month='March' year='2003' /></front>
<seriesInfo name='RFC' value='3490' />
<format type='TXT' octets='51943' target='ftp://ftp.isi.edu/in-notes/rfc3490.txt' />
</reference>
<reference anchor="NAMEPREP">
<front>
<title>Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)</title>
<author initials='P.' surname='Hoffman' fullname='P. Hoffman'>
<organization /></author>
<author initials='M.' surname='Blanchet' fullname='M. Blanchet'>
<organization /></author>
<date month='March' year='2003' /></front>
<seriesInfo name='RFC' value='3491' />
<format type='TXT' octets='10316' target='ftp://ftp.isi.edu/in-notes/rfc3491.txt' />
</reference>
<reference anchor="STRINGPREP">
<front>
<title>Preparation of Internationalized Strings ("stringprep")</title>
<author initials='P.' surname='Hoffman' fullname='P. Hoffman'>
<organization /></author>
<author initials='M.' surname='Blanchet' fullname='M. Blanchet'>
<organization /></author>
<date month='December' year='2002' /></front>
<seriesInfo name='RFC' value='3454' />
<format type='TXT' octets='138684' target='ftp://ftp.isi.edu/in-notes/rfc3454.txt' />
</reference>
<reference anchor="TERMS">
<front>
<title abbrev='RFC Key Words'>Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials='S.' surname='Bradner' fullname='Scott Bradner'>
<organization>Harvard University</organization>
<address>
<postal>
<street>1350 Mass. Ave.</street>
<street>Cambridge</street>
<street>MA 02138</street></postal>
<phone>- +1 617 495 3864</phone>
<email>sob@harvard.edu</email></address></author>
<date month='March' year='1997' />
<area>General</area>
<keyword>keyword</keyword>
<abstract>
<t>
In many standards track documents several words are used to signify
the requirements in the specification. These words are often
capitalized. This document defines these words as they should be
interpreted in IETF documents. Authors who follow these guidelines
should incorporate this phrase near the beginning of their document:
<list>
<t>
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
RFC 2119.
</t></list></t>
<t>
Note that the force of these words is modified by the requirement
level of the document in which they are used.
</t></abstract></front>
<seriesInfo name='BCP' value='14' />
<seriesInfo name='RFC' value='2119' />
<format type='TXT' octets='4723' target='ftp://ftp.isi.edu/in-notes/rfc2119.txt' />
<format type='HTML' octets='14486' target='http://xml.resource.org/public/rfc/html/rfc2119.html' />
<format type='XML' octets='5661' target='http://xml.resource.org/public/rfc/xml/rfc2119.xml' />
</reference>
<reference anchor="UNICODE">
<front>
<title>The Unicode Standard, Version 3.2.0</title>
<author>
<organization>The Unicode Consortium</organization>
</author>
<date year="2000" />
</front>
<annotation>
The Unicode Standard, Version 3.2.0 is defined by The Unicode Standard, Version 3.0 (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5), as amended by the Unicode Standard Annex #27: Unicode 3.1 (http://www.unicode.org/reports/tr27/) and by the Unicode Standard Annex #28: Unicode 3.2 (http://www.unicode.org/reports/tr28/).
</annotation>
</reference>
<reference anchor='UTF-8'>
<front>
<title>UTF-8, a transformation format of ISO 10646</title>
<author initials='F.' surname='Yergeau' fullname='F. Yergeau'>
<organization /></author>
<date month='November' year='2003' /></front>
<seriesInfo name='STD' value='63' />
<seriesInfo name='RFC' value='3629' />
<format type='TXT' octets='33856' target='ftp://ftp.isi.edu/in-notes/rfc3629.txt' />
</reference>
<reference anchor="XMPP">
<front>
<title>Extensible Messaging and Presence Protocol (XMPP): Core</title>
<author initials='P' surname='Saint-Andre' fullname='Peter Saint-Andre'>
<organization />
</author>
<date month='March' day='31' year='2010' />
<abstract><t>This document defines the core features of the Extensible Messaging and Presence Protocol (XMPP), a technology for streaming Extensible Markup Language (XML) elements in order to exchange structured information in close to real time between any two or more network- aware entities. XMPP provides a generalized, extensible framework for incrementally exchanging XML data, upon which a variety of applications can be built. The framework includes methods for stream setup and teardown, channel encryption, authentication of a client to a server and of one server to another server, and primitives for push-style messages, publication of network availability information ("presence"), and request-response interactions between any two XMPP entities. This document obsoletes RFC 3920.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-ietf-xmpp-3920bis-06' />
<format type='TXT'
target='http://www.ietf.org/internet-drafts/draft-ietf-xmpp-3920bis-06.txt' />
</reference>
</references>
<references title="Informative References">
<reference anchor='DNS'>
<front>
<title abbrev='Domain Implementation and Specification'>Domain names - implementation and specification</title>
<author initials='P.' surname='Mockapetris' fullname='P. Mockapetris'>
<organization>USC/ISI</organization>
<address>
<postal>
<street>4676 Admiralty Way</street>
<city>Marina del Rey</city>
<region>CA</region>
<code>90291</code>
<country>US</country></postal>
<phone>+1 213 822 1511</phone></address></author>
<date month='November' day='1' year='1987' /></front>
<seriesInfo name='STD' value='13' />
<seriesInfo name='RFC' value='1035' />
<format type='TXT' octets='125626' target='ftp://ftp.isi.edu/in-notes/rfc1035.txt' />
</reference>
<reference anchor='DNSSEC'>
<front>
<title>DNS Security Introduction and Requirements</title>
<author initials='R.' surname='Arends' fullname='R. Arends'>
<organization /></author>
<author initials='R.' surname='Austein' fullname='R. Austein'>
<organization /></author>
<author initials='M.' surname='Larson' fullname='M. Larson'>
<organization /></author>
<author initials='D.' surname='Massey' fullname='D. Massey'>
<organization /></author>
<author initials='S.' surname='Rose' fullname='S. Rose'>
<organization /></author>
<date year='2005' month='March' />
<abstract>
<t>The Domain Name System Security Extensions (DNSSEC) add data origin authentication and data integrity to the Domain Name System. This document introduces these extensions and describes their capabilities and limitations. This document also discusses the services that the DNS security extensions do and do not provide. Last, this document describes the interrelationships between the documents that collectively describe DNSSEC. [STANDARDS TRACK] </t></abstract></front>
<seriesInfo name='RFC' value='4033' />
<format type='TXT' octets='52445' target='ftp://ftp.isi.edu/in-notes/rfc4033.txt' />
</reference>
<reference anchor='IDNA-DEFS'>
<front>
<title>Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework</title>
<author initials='J' surname='Klensin' fullname='John Klensin'>
<organization />
</author>
<date month='January' day='7' year='2010' />
<abstract><t>This document is one of a collection that, together, describe the protocol and usage context for a revision of Internationalized Domain Names for Applications (IDNA), superseding the earlier version. It describes the document collection and provides definitions and other material that are common to the set.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-ietf-idnabis-defs-13' />
<format type='TXT'
target='http://www.ietf.org/internet-drafts/draft-ietf-idnabis-defs-13.txt' />
</reference>
<reference anchor='INTEROP'>
<front>
<title>Formalizing IETF Interoperability Reporting</title>
<author initials='L' surname='Masinter' fullname='Larry Masinter'>
<organization />
</author>
<date month='October' day='12' year='2005' />
<abstract><t>This document suggests another way of reforming IETF standards process by formalizing the mechanism for interoperability reporting, as a way of facilitating standards development. It establishes two kinds of reports: a 'Protocol Feature Set', which lays out the set of features from IETF specifications that constitute a protocol, and a 'Protocol Implementation Report', which is submitted by an individual or group to report on implementation and interoperability testing.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-ietf-newtrk-interop-reports-00' />
<format type='TXT'
target='http://www.ietf.org/internet-drafts/draft-ietf-newtrk-interop-reports-00.txt' />
</reference>
<reference anchor='IRI'>
<front>
<title>Internationalized Resource Identifiers (IRIs)</title>
<author initials='M.' surname='Duerst' fullname='M. Duerst'>
<organization /></author>
<author initials='M.' surname='Suignard' fullname='M. Suignard'>
<organization /></author>
<date year='2005' month='January' />
<abstract>
<t><p>This document defines a new protocol element, the Internationalized Resource Identifier (IRI), as a complement of the Uniform Resource Identifier (URI). An IRI is a sequence of characters from the Universal Character Set (Unicode/ISO 10646). A mapping from IRIs to URIs is defined, which means that IRIs can be used instead of URIs, where appropriate, to identify resources.</p><p> The approach of defining a new protocol element was chosen instead of extending or changing the definition of URIs. This was done in order to allow a clear distinction and to avoid incompatibilities with existing software. Guidelines are provided for the use and deployment of IRIs in various protocols, formats, and software components that currently deal with URIs.</p></t></abstract></front>
<seriesInfo name='RFC' value='3987' />
<format type='TXT' octets='111190' target='ftp://ftp.isi.edu/in-notes/rfc3987.txt' />
</reference>
<reference anchor='PROCESS'>
<front>
<title abbrev='Internet Standards Process'>The Internet Standards Process -- Revision 3</title>
<author initials='S.' surname='Bradner' fullname='Scott O. Bradner'>
<organization>Harvard University</organization>
<address>
<postal>
<street>1350 Mass. Ave.</street>
<city>Cambridge</city>
<region>MA</region>
<code>02138</code>
<country>US</country></postal>
<phone>+1 617 495 3864</phone>
<email>sob@harvard.edu</email></address></author>
<date year='1996' month='October' />
<abstract>
<t>This memo documents the process used by the Internet community for the standardization of protocols and procedures. It defines the stages in the standardization process, the requirements for moving a document between stages and the types of documents used during this process. It also addresses the intellectual property rights and copyright issues associated with the standards process.</t></abstract></front>
<seriesInfo name='BCP' value='9' />
<seriesInfo name='RFC' value='2026' />
<format type='TXT' octets='86731' target='ftp://ftp.isi.edu/in-notes/rfc2026.txt' />
</reference>
<reference anchor='PUNYCODE'>
<front>
<title>Punycode: A Bootstring encoding of Unicode for Internationalized Domain Names in Applications (IDNA)</title>
<author initials='A.' surname='Costello' fullname='A. Costello'>
<organization /></author>
<date year='2003' month='March' />
<abstract>
<t>Punycode is a simple and efficient transfer encoding syntax designed for use with Internationalized Domain Names in Applications (IDNA). It uniquely and reversibly transforms a Unicode string into an ASCII string. ASCII characters in the Unicode string are represented literally, and non-ASCII characters are represented by ASCII characters that are allowed in host name labels (letters, digits, and hyphens). This document defines a general algorithm called Bootstring that allows a string of basic code points to uniquely represent any string of code points drawn from a larger set. Punycode is an instance of Bootstring that uses particular parameter values specified by this document, appropriate for IDNA. [STANDARDS TRACK] </t></abstract></front>
<seriesInfo name='RFC' value='3492' />
<format type='TXT' octets='67439' target='ftp://ftp.isi.edu/in-notes/rfc3492.txt' />
</reference>
<reference anchor='REPORTS'>
<front>
<title>Guidance on Interoperation and Implementation Reports for Advancement to Draft Standard</title>
<author initials='L.' surname='Dusseault' fullname='L. Dusseault'>
<organization /></author>
<author initials='R.' surname='Sparks' fullname='R. Sparks'>
<organization /></author>
<date year='2009' month='September' />
<abstract>
<t>Advancing a protocol to Draft Standard requires documentation of the interoperation and implementation of the protocol. Historic reports have varied widely in form and level of content and there is little guidance available to new report preparers. This document updates the existing processes and provides more detail on what is appropriate in an interoperability and implementation report. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t></abstract></front>
<seriesInfo name='BCP' value='9' />
<seriesInfo name='RFC' value='5657' />
<format type='TXT' octets='29327' target='ftp://ftp.isi.edu/in-notes/rfc5657.txt' />
</reference>
<reference anchor='RFC3920'>
<front>
<title abbrev='XMPP Core'>Extensible Messaging and Presence Protocol (XMPP): Core</title>
<author initials='P.' surname='Saint-Andre' fullname='Peter Saint-Andre' role='editor'>
<organization>Jabber Software Foundation</organization>
<address>
<email>stpeter@jabber.org</email></address></author>
<date year='2004' month='October' />
<area>Applications</area>
<workgroup>XMPP Working Group</workgroup>
<keyword>RFC</keyword>
<keyword>Request for Comments</keyword>
<keyword>I-D</keyword>
<keyword>Internet-Draft</keyword>
<keyword>XMPP</keyword>
<keyword>Extensible Messaging and Presence Protocol</keyword>
<keyword>Jabber</keyword>
<keyword>IM</keyword>
<keyword>Instant Messaging</keyword>
<keyword>Presence</keyword>
<keyword>XML</keyword>
<keyword>Extensible Markup Language</keyword>
<abstract>
<t>This memo defines the core features of the Extensible Messaging and Presence Protocol (XMPP), a protocol for streaming Extensible Markup Language (XML) elements in order to exchange structured information in close to real time between any two network endpoints. While XMPP provides a generalized, extensible framework for exchanging XML data, it is used mainly for the purpose of building instant messaging and presence applications that meet the requirements of RFC 2779.</t></abstract></front>
<seriesInfo name='RFC' value='3920' />
<format type='TXT' octets='194313' target='ftp://ftp.isi.edu/in-notes/rfc3920.txt' />
<format type='HTML' octets='279912' target='http://xml.resource.org/public/rfc/html/rfc3920.html' />
<format type='XML' octets='234610' target='http://xml.resource.org/public/rfc/xml/rfc3920.xml' />
</reference>
<reference anchor='URI'>
<front>
<title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
<author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
<organization abbrev='W3C/MIT'>World Wide Web Consortium</organization>
<address>
<postal>
<street>Massachusetts Institute of Technology</street>
<street>77 Massachusetts Avenue</street>
<city>Cambridge</city>
<region>MA</region>
<code>02139</code>
<country>USA</country></postal>
<phone>+1-617-253-5702</phone>
<facsimile>+1-617-258-5999</facsimile>
<email>timbl@w3.org</email>
<uri>http://www.w3.org/People/Berners-Lee/</uri></address></author>
<author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
<organization abbrev='Day Software'>Day Software</organization>
<address>
<postal>
<street>5251 California Ave., Suite 110</street>
<city>Irvine</city>
<region>CA</region>
<code>92617</code>
<country>USA</country></postal>
<phone>+1-949-679-2960</phone>
<facsimile>+1-949-679-2972</facsimile>
<email>fielding@gbiv.com</email>
<uri>http://roy.gbiv.com/</uri></address></author>
<author initials='L.' surname='Masinter' fullname='Larry Masinter'>
<organization abbrev='Adobe Systems'>Adobe Systems Incorporated</organization>
<address>
<postal>
<street>345 Park Ave</street>
<city>San Jose</city>
<region>CA</region>
<code>95110</code>
<country>USA</country></postal>
<phone>+1-408-536-3024</phone>
<email>LMM@acm.org</email>
<uri>http://larry.masinter.net/</uri></address></author>
<date year='2005' month='January' />
<area>Applications</area>
<keyword>uniform resource identifier</keyword>
<keyword>URI</keyword>
<keyword>URL</keyword>
<keyword>URN</keyword>
<keyword>WWW</keyword>
<keyword>resource</keyword>
<abstract>
<t>
A Uniform Resource Identifier (URI) is a compact sequence of characters
that identifies an abstract or physical resource. This specification
defines the generic URI syntax and a process for resolving URI references
that might be in relative form, along with guidelines and security
considerations for the use of URIs on the Internet.
The URI syntax defines a grammar that is a superset of all valid URIs,
allowing an implementation to parse the common components of a URI
reference without knowing the scheme-specific requirements of every
possible identifier. This specification does not define a generative
grammar for URIs; that task is performed by the individual
specifications of each URI scheme.
</t></abstract></front>
<seriesInfo name='STD' value='66' />
<seriesInfo name='RFC' value='3986' />
<format type='TXT' octets='141811' target='ftp://ftp.isi.edu/in-notes/rfc3986.txt' />
<format type='HTML' octets='200858' target='http://xml.resource.org/public/rfc/html/rfc3986.html' />
<format type='XML' octets='165759' target='http://xml.resource.org/public/rfc/xml/rfc3986.xml' />
</reference>
<reference anchor="XEP-0029">
<front>
<title>Definition of Jabber Identifiers (JIDs)</title>
<author initials="C." surname="Kaes" fullname="Craig Kaes">
<organization/>
<address>
<email>craigk@jabber.com</email>
</address>
</author>
<date day="03" month="October" year="2003"/>
</front>
<seriesInfo name="XSF XEP" value="0029"/>
<format type="HTML" target="http://xmpp.org/extensions/xep-0029.html"/>
</reference>
<reference anchor="XEP-0030">
<front>
<title>Service Discovery</title>
<author initials="J." surname="Hildebrand" fullname="Joe Hildebrand">
<organization/>
<address>
<email>jhildebr@cisco.com</email>
</address>
</author>
<author initials="P." surname="Millard" fullname="Peter Millard">
<organization/>
<address>
<email/>
</address>
</author>
<author initials="R." surname="Eatmon" fullname="Ryan Eatmon">
<organization/>
<address>
<email>reatmon@jabber.org</email>
</address>
</author>
<author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
<organization/>
<address>
<email>stpeter@jabber.org</email>
</address>
</author>
<date day="06" month="June" year="2008"/>
</front>
<seriesInfo name="XSF XEP" value="0030"/>
<format type="HTML" target="http://xmpp.org/extensions/xep-0030.html"/>
</reference>
<reference anchor="XEP-0045">
<front>
<title>Multi-User Chat</title>
<author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
<organization/>
<address>
<email>stpeter@jabber.org</email>
</address>
</author>
<date day="21" month="January" year="in progress, last updated 2010"/>
</front>
<seriesInfo name="XSF XEP" value="0045"/>
<format type="HTML" target="http://xmpp.org/extensions/xep-0045.html"/>
</reference>
<reference anchor="XEP-0060">
<front>
<title>Publish-Subscribe</title>
<author initials="P." surname="Millard" fullname="Peter Millard">
<organization/>
<address>
<email/>
</address>
</author>
<author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
<organization/>
<address>
<email>stpeter@jabber.org</email>
</address>
</author>
<author initials="R." surname="Meijer" fullname="Ralph Meijer">
<organization/>
<address>
<email>ralphm@ik.nu</email>
</address>
</author>
<date day="03" month="September" year="2008"/>
</front>
<seriesInfo name="XSF XEP" value="0060"/>
<format type="HTML" target="http://xmpp.org/extensions/xep-0060.html"/>
</reference>
<reference anchor="XEP-0165">
<front>
<title>Best Practices to Prevent JID Mimicking</title>
<author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
<organization/>
<address>
<email>stpeter@jabber.org</email>
</address>
</author>
<date day="13" month="December" year="2007"/>
</front>
<seriesInfo name="XSF XEP" value="0165"/>
<format type="HTML" target="http://www.xmpp.org/extensions/xep-0165.html"/>
</reference>
<reference anchor="XEP-0271">
<front>
<title>XMPP Nodes</title>
<author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
<organization/>
<address>
<email>stpeter@jabber.org</email>
</address>
</author>
<author initials="R." surname="Meijer" fullname="Ralph Meijer">
<organization/>
<address>
<email>ralphm@ik.nu</email>
</address>
</author>
<date day="26" month="June" year="2009"/>
</front>
<seriesInfo name="XSF XEP" value="0271"/>
<format type="HTML" target="http://xmpp.org/extensions/xep-0271.html"/>
</reference>
<reference anchor='XML' target='http://www.w3.org/TR/2006/REC-xml-20060816'>
<front>
<title>Extensible Markup Language (XML) 1.0 (Fourth Edition)</title>
<author initials='J.' surname='Paoli' fullname='Jean Paoli'>
<organization />
</author>
<author initials='E.' surname='Maler' fullname='Eve Maler'>
<organization />
</author>
<author initials='C.' surname='Sperberg-McQueen' fullname='C. M. Sperberg-McQueen'>
<organization />
</author>
<author initials='F.' surname='Yergeau' fullname='François Yergeau'>
<organization />
</author>
<author initials='T.' surname='Bray' fullname='Tim Bray'>
<organization />
</author>
<date month='August' day='16' year='2006' />
</front>
<seriesInfo name='World Wide Web Consortium Recommendation' value='REC-xml-20060816' />
<format type='HTML' target='http://www.w3.org/TR/2006/REC-xml-20060816' />
</reference>
<reference anchor='XMPP-URI'>
<front>
<title>Internationalized Resource Identifiers (IRIs) and Uniform Resource Identifiers (URIs) for the Extensible Messaging and Presence Protocol (XMPP)</title>
<author initials='P.' surname='Saint-Andre' fullname='P. Saint-Andre'>
<organization /></author>
<date year='2008' month='February' />
<abstract>
<t>This document defines the use of Internationalized Resource Identifiers (IRIs) and Uniform Resource Identifiers (URIs) in identifying or interacting with entities that can communicate via the Extensible Messaging and Presence Protocol (XMPP). [STANDARDS TRACK]</t></abstract></front>
<seriesInfo name='RFC' value='5122' />
<format type='TXT' octets='55566' target='ftp://ftp.isi.edu/in-notes/rfc5122.txt' />
</reference>
</references>
<section title="Nodeprep" anchor="nodeprep">
<section title="Introduction" anchor="nodeprep-intro">
<t>This appendix defines the "Nodeprep" profile of stringprep. As such, it specifies processing rules that will enable users to enter internationalized localparts in the Extensible Messaging and Presence Protocol (XMPP) and have the highest chance of getting the content of the strings correct. (An XMPP localpart is the optional portion of an XMPP address that precedes an XMPP domainpart and the '@' separator; it is often but not exclusively associated with an instant messaging username.) These processing rules are intended only for XMPP localparts and are not intended for arbitrary text or any other aspect of an XMPP address.</t>
<t>This profile defines the following, as required by <xref target="STRINGPREP"/>:</t>
<t><list style="symbols">
<t>The intended applicability of the profile: internationalized localparts within XMPP</t>
<t>The character repertoire that is the input and output to stringprep: Unicode 3.2, specified in Section 2 of this Appendix</t>
<t>The mappings used: specified in Section 3</t>
<t>The Unicode normalization used: specified in Section 4</t>
<t>The characters that are prohibited as output: specified in Section 5</t>
<t>Bidirectional character handling: specified in Section 6</t>
</list></t>
</section>
<section title="Character Repertoire" anchor="nodeprep-character">
<t>This profile uses Unicode 3.2 with the list of unassigned code points being Table A.1, both defined in Appendix A of <xref target="STRINGPREP"/>.</t>
</section>
<section title="Mapping" anchor="nodeprep-mapping">
<t>This profile specifies mapping using the following tables from <xref target="STRINGPREP"/>:</t>
<t><list style='hanging'>
<t>Table B.1</t>
<t>Table B.2</t>
</list></t>
</section>
<section title="Normalization" anchor="nodeprep-normalization">
<t>This profile specifies the use of Unicode normalization form KC, as described in <xref target="STRINGPREP"/>.</t>
</section>
<section title="Prohibited Output" anchor="nodeprep-prohibited">
<t>This profile specifies the prohibition of using the following tables from <xref target="STRINGPREP"/>.</t>
<t><list style='hanging'>
<t>Table C.1.1</t>
<t>Table C.1.2</t>
<t>Table C.2.1</t>
<t>Table C.2.2</t>
<t>Table C.3</t>
<t>Table C.4</t>
<t>Table C.5</t>
<t>Table C.6</t>
<t>Table C.7</t>
<t>Table C.8</t>
<t>Table C.9</t>
</list></t>
<t>In addition, the following additional Unicode characters are also prohibited:</t>
<t>
<list style='hanging'>
<t>U+0022 (QUOTATION MARK), i.e., "</t>
<t>U+0026 (AMPERSAND), i.e., &</t>
<t>U+0027 (APOSTROPHE), i.e., '</t>
<t>U+002F (SOLIDUS), i.e., /</t>
<t>U+003A (COLON), i.e., :</t>
<t>U+003C (LESS-THAN SIGN), i.e., <</t>
<t>U+003E (GREATER-THAN SIGN), i.e., ></t>
<t>U+0040 (COMMERCIAL AT), i.e., @</t>
</list>
</t>
</section>
<section title="Bidirectional Characters" anchor="nodeprep-bidirectional">
<t>This profile specifies checking bidirectional strings, as described in Section 6 of <xref target="STRINGPREP"/>.</t>
</section>
<section title="Notes" anchor="nodeprep-notes">
<t>Because the additional characters prohibited by Nodeprep are prohibited after normalization, an implementation MUST NOT enable a human user to input any Unicode code point whose decomposition includes those characters; such code points include but are not necessarily limited to the following (refer to <xref target='UNICODE'/> for complete information).</t>
<t>
<list style='symbols'>
<t>U+2100 (ACCOUNT OF)</t>
<t>U+2101 (ADDRESSED TO THE SUBJECT)</t>
<t>U+2105 (CARE OF)</t>
<t>U+2106 (CADA UNA)</t>
<t>U+226E (NOT LESS-THAN)</t>
<t>U+226F (NOT GREATER-THAN)</t>
<t>U+2A74 (DOUBLE COLON EQUAL)</t>
<t>U+FE13 (SMALL COLON)</t>
<t>U+FE60 (SMALL AMPERSAND)</t>
<t>U+FE64 (SMALL LESS-THAN SIGN)</t>
<t>U+FE65 (SMALL GREATER-THAN SIGN)</t>
<t>U+FE6B (SMALL COMMERCIAL AT)</t>
<t>U+FF02 (FULLWIDTH QUOTATION MARK)</t>
<t>U+FF06 (FULLWIDTH AMPERSAND)</t>
<t>U+FF07 (FULLWIDTH APOSTROPHE)</t>
<t>U+FF0F (FULLWIDTH SOLIDUS)</t>
<t>U+FF1A (FULLWIDTH COLON)</t>
<t>U+FF1C (FULLWIDTH LESS-THAN SIGN)</t>
<t>U+FF1E (FULLWIDTH GREATER-THAN SIGN)</t>
<t>U+FF20 (FULLWIDTH COMMERCIAL AT)</t>
</list>
</t>
</section>
</section>
<section title="Resourceprep" anchor="resourceprep">
<section title="Introduction" anchor="resourceprep-introduction">
<t>This appendix defines the "Resourceprep" profile of stringprep. As such, it specifies processing rules that will enable users to enter internationalized resourceparts in the Extensible Messaging and Presence Protocol (XMPP) and have the highest chance of getting the content of the strings correct. (An XMPP resourcepart is the optional portion of an XMPP address that follows an XMPP domainpart and the '/' separator.) These processing rules are intended only for XMPP resourceparts and are not intended for arbitrary text or any other aspect of an XMPP address.</t>
<t>This profile defines the following, as required by <xref target="STRINGPREP"/>:</t>
<t><list style="symbols">
<t>The intended applicability of the profile: internationalized resourceparts within XMPP</t>
<t>The character repertoire that is the input and output to stringprep: Unicode 3.2, specified in Section 2 of this Appendix</t>
<t>The mappings used: specified in Section 3</t>
<t>The Unicode normalization used: specified in Section 4</t>
<t>The characters that are prohibited as output: specified in Section 5</t>
<t>Bidirectional character handling: specified in Section 6</t>
</list></t>
</section>
<section title="Character Repertoire" anchor="resourceprep-character">
<t>This profile uses Unicode 3.2 with the list of unassigned code points being Table A.1, both defined in Appendix A of <xref target="STRINGPREP"/>.</t>
</section>
<section title="Mapping" anchor="resourceprep-mapping">
<t>This profile specifies mapping using the following tables from <xref target="STRINGPREP"/>:</t>
<t><list style='hanging'>
<t>Table B.1</t>
</list></t>
</section>
<section title="Normalization" anchor="resourceprep-normalization">
<t>This profile specifies the use of Unicode normalization form KC, as described in <xref target="STRINGPREP"/>.</t>
</section>
<section title="Prohibited Output" anchor="resourceprep-prohibited">
<t>This profile specifies the prohibition of using the following tables from <xref target="STRINGPREP"/>.</t>
<t><list style='hanging'>
<t>Table C.1.2</t>
<t>Table C.2.1</t>
<t>Table C.2.2</t>
<t>Table C.3</t>
<t>Table C.4</t>
<t>Table C.5</t>
<t>Table C.6</t>
<t>Table C.7</t>
<t>Table C.8</t>
<t>Table C.9</t>
</list></t>
</section>
<section title="Bidirectional Characters" anchor="resourceprep-bidirectional">
<t>This profile specifies checking bidirectional strings, as described in Section 6 of <xref target="STRINGPREP"/>.</t>
</section>
</section>
<section title="Differences From RFC 3920" anchor="diffs">
<t>Based on consensus derived from implementation and deployment experience as well as formal interoperability testing, the following substantive modifications were made from RFC 3920.</t>
<t>
<list style='symbols'>
<t>Corrected the ABNF syntax for JIDs to prevent zero-length localparts, domainparts, and resourceparts.</t>
<t>To avoid confusion with the term "node" as used in <xref target="XEP-0030"/> and <xref target="XEP-0060"/> (see also <xref target="XEP-0271"/>), changed the term "node identifier" to "localpart" (but retained the name "Nodeprep" for backward compatibility).</t>
<t>To avoid confusion with the terms "resource" and "identifier" as used in <xref target="URI"/>, changed the term "resource identifier" to "resourcepart".</t>
<t>Corrected the nameprep processing rules to require use of the UseSTD3ASCIIRules flag.</t>
</list>
</t>
</section>
<section title="Copying Conditions" anchor="copying">
<t>Regarding this entire document or any portion of it, the author makes no guarantees and is not responsible for any damage resulting from its use. The author grants irrevocable permission to anyone to use, modify, and distribute it in any way that does not diminish the rights of anyone else to use, modify, and distribute it, provided that redistributed derivative works do not contain misleading author or version information. Derivative works need not be licensed under similar terms.</t>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-23 10:15:04 |