mirror of
https://github.com/moparisthebest/xeps
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210 lines
11 KiB
XML
210 lines
11 KiB
XML
<?xml version='1.0' encoding='UTF-8'?>
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<!DOCTYPE xep SYSTEM 'xep.dtd' [
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<!ENTITY % ents SYSTEM 'xep.ent'>
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%ents;
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<!ENTITY ns "urn:xmpp:mamfc:0">
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<!ENTITY nsx "urn:example:">
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]>
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<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
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<xep>
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<header>
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<title>MAM Fastening Collation</title>
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<abstract>This specification proposes a mechanism by which MAM results containing fastenings can be collated effectively.</abstract>
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&LEGALNOTICE;
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<number>0427</number>
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<status>Experimental</status>
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<type>Standards Track</type>
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<sig>Standards</sig>
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<dependencies>
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<spec>XMPP Core</spec>
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<spec>XEP-0422</spec>
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<spec>XEP-0313</spec>
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</dependencies>
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<supersedes/>
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<supersededby/>
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<shortname>mamfc</shortname>
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&dcridland;
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&ksmithisode;
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<revision>
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<version>0.1.0</version>
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<date>2020-01-28</date>
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<initials>XEP Editor (jsc)</initials>
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<remark>Accepted by vote of Council on 2020-01-02.</remark>
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</revision>
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<revision>
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<version>0.0.1</version>
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<date>2019-12-19</date>
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<initials>dwd</initials>
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<remark>
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<ul>
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<li>Initial Revision</li>
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</ul>
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</remark>
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</revision>
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</header>
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<section1 topic='Introduction' anchor='intro'>
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<p>In XMPP, all messages are not equal. Some are semantically actual human messages; these are referred to in this
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document as "instant messages". Others are ancillary messages - reactions, receipts, and so on - that are useful
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and important, but do not conform to the concept of an instant message in the sense that a user might reasonably
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expect.</p>
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<p>Fastenings, &xep0422;, provides a generic mechanism for a sending entity to indicate that a particular message is
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associated closely to an instant message. But in doing so, this presents the problem that if many messages are not in fact
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actual human messages, an archive query might end up downloading dozens or even hundreds of messages in order to
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present just a handful of actual instant messages to the user. Much of the information downloaded is not required.</p>
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<p>For example, to display a message, a client may need to download all the "likes" for it - whereas a simply number of
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likes might be sufficient for most users' needs.</p>
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<p>This specification tackles the problem by allowing these to be filtered, collated, or presented in full depending
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on the needs of the client. The client now downloads just the instant messages from the archive, and any likes,
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reactions, or receipts are simply summarized.</p>
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<section2 topic="Terminology">
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<p>Because this document defines mechanisms for dealing generically with potential types of fastenings, it does not
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offer any real examples of actual fastenings that might be used.</p>
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<p>Instead, example fastenings are used within an XML namespace prefixed by <tt>&nsx;</tt></p>
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<p>Pseudo-fastenings are messages that are semantically equivalent to fastenings, but use a different syntax,
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see <link url="#pseudo">Pseudo Fastenings</link>.</p>
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<p>Nomenclature used for instant messages versus ancillary messages will need to be adjusted to make it consistent
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with &xep0422; et al.</p>
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</section2>
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</section1>
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<section1 topic='Overview' anchor="overview">
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<section2 topic="Discovering Support" anchor="feature">
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<p>Support for this protocol is advertised by the Service Discovery protocol defined in &xep0030; using a feature
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of <tt>&ns;</tt>.</p>
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</section2>
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<section2 topic="Summarizing">
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<p>This specification provides for four types of summary listing.</p>
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<p>The first form, "<tt>simplified</tt>", is the default, and essentially represents the status quo. MAM queries
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behave as if the archive contains only traditional IM traffic. No summary is provided.</p>
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<p>The second form, "<tt>full</tt>", presents every message stanza in the results, including all fastenings,
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errors, and so on.</p>
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<p>The third form, "<tt>collate</tt>", presents each traditional IM message, as "<tt>simplified</tt>", but within
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the result includes summary information about the fastenings (and pseudo-fastenings) encountered.</p>
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<p>Finally a fourth form, "<tt>fastenings</tt>", returns only the fastenings for a particular message.</p>
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<p>The "collate" form is the bulk of the specification presented herein.</p>
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<section3 topic="Summary Information">
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<p>The <apply-to/> element of &xep0422; contains a number of fastening elements. These in turn consist of a
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qualified element, with a number of attributes, and potentially some content within the element.</p>
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<p>This specification refers to the qualified name (the tuple of XML namespace and local-name) as the "fastening
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type" (represented as an XML element herein), and the top-level element (including attributes and their
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values), as the "fastening summary".</p>
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<p>For example, a hypothetical edit fastening type might be <tt><edit xmlns="&nsx;edit:0"/></tt>, and that would
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be the fastening summary as well. The full fastening would include any children (text or further XML elements)
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of the top-level element. But a hypothetical reaction fastening type might be
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<tt><reaction xmlns="&nsx;reaction:0"/></tt>, but the fastening summary could be
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<tt><reaction xmlns="&nsx;reaction:0" emoji="Ὁ"/></tt></p>
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<p>The summary information against each parent message consists of, for each fastening summary:</p>
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<ul>
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<li>The fastening summary itself.</li>
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<li>A count of the number of fastenings with this summary fastened to the parent message.</li>
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<li>The full fastening for the last fastening received for the parent message.</li>
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</ul>
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</section3>
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</section2>
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</section1>
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<section1 topic="Protocol Elements">
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<section2 topic="Querying">
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<p>This specification adds an additional field to the form defined in &xep0313; with the field name
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"<tt>{&ns;}summary</tt>". This may have only the following values (unless of course further values are advertised
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by a future specification):</p>
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<ul>
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<li>simplified</li>
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<li>full</li>
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<li>collate</li>
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<li>fastenings</li>
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</ul>
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</section2>
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<section2 topic="Results">
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<p>The <tt><result/></tt> element defined in &xep0313; is extended by adding zero or more additional elements with
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a local name of "<tt>applied</tt>", qualified by the "<tt>&ns;</tt>" namespace.</p>
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<p>Each <tt><applied/></tt> element is associated with precisely one fastening summary.</p>
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<p>This element contains, as its first child element, the full fastening for the last fastening received by the
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server for the parent message. This is not included for "<tt>shell</tt>" fastenings, which are untyped.</p>
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<p>There is a "<tt>count</tt>" attribute, consisting of an integral count of the fastenings with the same summary
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as the first child element (or the count of shell fastenings when this is not included). This count, if absent,
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defaults to 1. For "<tt>shell</tt>" fastenings, the attribute "<tt>shell</tt>" is set to true (or another value
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with the same semantics for an XML boolean).</p>
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<p>The <tt><applied/></tt> elements are only included in the <tt><result/></tt> element when the requested
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summary type is "<tt>collate</tt>".</p>
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</section2>
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<section2 topic="Latest Archive ID">
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<p>The latest archive id can usually be deduced either from the last message stanza received (and its stanza-id,
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see &xep0359;) or by the id attribute of the last <tt><result/></tt> element from a query extending to the
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latest message.</p>
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<p>Since this specification can cause the latest message to be only in a summarized form when presented in the
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archive, it also adds an additional element to the <tt><fin/></tt> element which terminates the query, to
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indicate the latest id held in the archive (which may be that of a fastening).</p>
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<p>This element, qualified by the "<tt>&ns;</tt>", has the local name of "<tt>latest</tt>" and a single attribute,
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"<tt>id</tt>", containing the latest archive id.</p>
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</section2>
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<section2 topic="Incremental queries">
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<p>A MAM query where the MAM summary type is "<tt>collate</tt>", and where "<tt>start</tt>" and "<tt>end</tt>" (or
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the RSM <tt><after/></tt> element) would exclude the parent message but include the fastening, then the MAM
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result is sent with the <tt><forwarded/></tt> element omitted but the summary present (including all
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fastenings, not just those that have changed).</p>
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</section2>
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</section1>
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<section1 topic="Pseudo-Fastenings" anchor="pseudo">
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<p>A number of previous specifications exist that - if they were rewritten today - might use fastenings.</p>
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<p>For the purposes of this specification, it is convenient to treat these as pseudo-fastenings, behaving as if they
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were a fastening for the purposes of the "collate" and "fastenings" summary types.</p>
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<p>This specification defines two such types. Both MUST be supported by servers:</p>
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<ul>
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<li>Message Delivery Receipts: &xep0184; "ack messages" - those containing a <tt><received/></tt> element - are
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considered to be equivalent to a fastening containing just the <received/> element, applying to the message
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given by the "<tt>id</tt>" attribute.</li>
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<li>Chat Markers: &xep0333; A Chat Marker is similarly equivalent to a fastening containing the Chat Marker, but
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applying to all previous messages (since previous messages can be assumed to have been read and or displayed,
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etc).</li>
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</ul>
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<p>In both cases, the fastening summary SHOULD omit the <tt>id</tt> attribute.</p>
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</section1>
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<section1 topic="Examples">
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<p>A firm TODO; contributions are welcome - and a good test of whether I've written the rest right!</p>
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</section1>
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<section1 topic="Schema">
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<code>
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<![CDATA[
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<?xml version="1.0" encoding="UTF-8"?>
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<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="]]>&ns;<![CDATA[" xmlns:xs="http://www.w3.org/2001/XMLSchema">
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<xs:element name="applied" type="mamfc:appliedType" xmlns:mamfc="]]>&ns;<![CDATA["/>
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<xs:complexType name="appliedType">
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<xs:sequence>
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<xs:any minOccurs="0" maxOccurs="1"/>
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<!-- Fastening summary, absent when shell is true -->
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</xs:sequence>
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<xs:attribute type="xs:positiveInteger" name="count" default="1"/>
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<xs:attribute type="xs:boolean" name="shell" default="false"/>
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</xs:complexType>
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<xs:element name="latest" type="mamfc:latestType" xmlns:mamfc="]]>&ns;<![CDATA["/>
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<xs:complexType name="latestType">
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<xs:attribute type="xs:string"/>
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</xs:complexType>
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</xs:schema>
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]]>
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</code>
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</section1>
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<section1 topic='Security Considerations' anchor='security'>
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<p>This specification imposes substantial workload for servers.</p>
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</section1>
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<section1 topic='IANA Considerations' anchor='iana'>
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<p>This XEP requires no interaction with &IANA;. </p>
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</section1>
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<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
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<p>None.</p>
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</section1>
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<section1 topic='Acknowledgements' anchor='ack'>
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<p>The authors wish to share any credit with many members of the community, including Marvin Wissfield.</p>
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</section1>
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</xep>
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