root/standards/draft-pfeiffer-cmml-current.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">

<!-- Todos: -->
<!-- * move to XML schema -->
<!-- * sort out how to combine with other XML modules -->
<!-- * sort out style sheets -->


<?rfc toc="yes"?>
<?rfc sortrefs="yes"?>

<rfc category="info" ipr="full3667" docName="draft-pfeiffer-cmml-xx">

  <front>
    <title abbrev="CMML">The Continuous Media Markup Language (CMML), Version 3.1</title>

    <author initials="S.P." surname="Pfeiffer" fullname="Silvia Pfeiffer">
        <organization abbrev="CSIRO">Commonwealth Scientific and
        Industrial Research Organisation CSIRO,
        Australia</organization>
        <address>
           <postal>
              <street>PO Box 76</street>
              <city>Epping</city>
              <region>NSW</region>
              <code>1710</code>
              <country>Australia</country>
           </postal>
           <phone>+61 2 9372 4180</phone>
           <email>Silvia.Pfeiffer@csiro.au</email>
           <uri>http://www.ict.csiro.au/</uri>
        </address>
    </author>

    <author initials="C.D." surname="Parker" fullname="Conrad D. Parker">
        <organization abbrev="CSIRO">Commonwealth Scientific and
        Industrial Research Organisation CSIRO,
        Australia</organization>
        <address>
           <postal>
              <street>PO Box 76</street>
              <city>Epping</city>
              <region>NSW</region>
              <code>1710</code>
              <country>Australia</country>
           </postal>
           <phone>+61 2 9372 4222</phone>
           <email>Conrad.Parker@csiro.au</email>
           <uri>http://www.ict.csiro.au/</uri>
        </address>
    </author>

    <author initials="A.T." surname="Pang" fullname="Andre T. Pang">
        <organization abbrev="CSIRO">Commonwealth Scientific and
        Industrial Research Organisation CSIRO,
        Australia</organization>
        <address>
           <postal>
              <street>PO Box 76</street>
              <city>Epping</city>
              <region>NSW</region>
              <code>1710</code>
              <country>Australia</country>
           </postal>
           <phone>+61 2 9372 4222</phone>
           <email>Andre.Pang@csiro.au</email>
           <uri>http://www.ict.csiro.au/</uri>
        </address>
    </author>

    <date month="March" year="2005"/>

    <abstract>
      <t>This specification defines the Continuous Media Markup
      Language (CMML), version 3.1, an <xref
      target="XML">XML-based</xref> markup language for
      time-continuous data. It is a sister document to the
      specification of the <xref target="ANX">Annodex</xref>
      annotation, indexing and hyperlinking format for time-continuous
      data. A CMML file is essentially a textual representation of an
      Annodex file.
      </t>

      <t>The tags of a CMML file provide for the creation of structured and
      unstructured annotations as well as hyperlinks and addressable
      named anchor points for clips of time-continuous data. Through
      its import tag, the CMML is also an authoring language for <xref
      target="ANX">Annodex</xref> streams. The tag names in use in
      CMML are similar to the ones in <xref target="XHTML">XHTML</xref>.
      </t>

      <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 <xref target="KEYWORDS">RFC 2119</xref>.
      </t>

    </abstract>
  </front>
  
  <middle>
    
    <!--**************-->
    <!-- Introduction -->
    <!--**************-->
    <section title="Introduction">

      <t>The Continuous Media Markup Language (CMML) specifies XML
      based markup for time-continuous data to allow it to become
      an integral part of the World Wide Web analogously
      to how HTML allowed text documents to become part of the Web.
      Therefore, format of the CMML derives much from XHTML.
      </t>

      <t>CMML allows the attachment of free-text annotations, metadata,
      captions and other textual information to clips of time-continuous
      data. This provides a timed, textual representation of the data that
      can be indexed by Web search engines.
      </t>

      <t>CMML also allows the attachment of a hyperlink to each clip of
      time-continuous data, enabling Web search engines to crawl the
      content. This also allows users to surf seamlessly between
      time-continuous data and other Web resources, integrating clips
      of media into the browsing history of a Web browser.
      </t>

      <t>CMML also provides a way of referencing a representative image
      for each clip of time-continuous data, providing a visual representation
      of the clip in conjunction with the textual representation. The
      expected usage scenario for this is in the presentation of search
      results or in a table of clips.
      </t>

      <t>CMML provides a "head" element to store information that
      concerns the complete time-continous resource, and a set of "clip"
      elements that each store information for a temporal subpart of the
      resource.
      </t>

      <t>The practical use of a CMML file is in conjunction with the
      <xref target="ANX">Annodex exchange format</xref>. CMML markup
      can be interleaved inside an Annodex file or stream to allow
      a synchronised delivery of marked-up time-continuous data
      in a single stream between a Web server and a user agent.
      </t>
      
      <t>CMML has also been designed as an authoring language for
      Annodex bitstreams. It allows the description of time-continuous
      data bitstream(s) that need to be multiplexed together to create
      an Annodex bitstream. This information is stored in the "stream"
      element of a CMML document. Such a document can be used to control
      the multiplexing process that creates an Annodex file.
      </t>

      <t>The following picture illustrates the multiplexing activity
      schematically; in reality, the stream tag is not preserved in its
      original form and some attribute values are also encoded in the binary
      data. Details of how CMML markup is encoded in an
      Annodex bitstream are given later in this document.
      </t>
      <figure>
        <artwork><![CDATA[
   ----------
   |stream  | CMML
   ---------- instance
   | head   | document
   ----------
   | clip_1 |     ----------------------------------------------------
   ----------     | data bitstream in packets                        |
   | ...    |     ----------------------------------------------------
   ----------          |
   | clip_n |          |
   ----------          |
       |               |
       ------->-<-------
               |          Multiplexing
               |
               v
---------------------------------------------------------------------
|stream|head|clip_1|  data packets         |clip_2| data packets  ...
---------------------------------------------------------------------
          ]]></artwork>
      </figure>
      
      <t>The CMML is technically fully specified through its DTD as
      given in the Appendix. The semantic meaning of each of the tags,
      their content and their attributes is specified in the following
      sections. The Appendix also contains an example of a CMML
      (instance) document.
      </t>

      <t>The file extension of CMML files is ".cmml". This document
      also applies for registration of the mime-type "text/cmml" for
      CMML files with IANA. In the meantime, "text/x-cmml" will be
      used.
      </t>

      <t>Please note that this document assumes that the reader has a
      fluent working knowledge of <xref target="XML">Extensible Markup
      Language (XML)</xref>, <xref target="HTML">Hypertext Markup
      Language (HTML)</xref>, <xref target="XHTML">XHTML</xref>,
      <xref target="CSS">Cascading Style Sheets (CSS)</xref> and
      the World Wide Web. Basic knowledge about the <xref
      target="ANX">Annodex</xref> format is also assumed.
      </t>

    </section>

    <!--************-->
    <!-- CMML types -->
    <!--************-->
    <section title="The CMML data types">

      <t>At the beginning of the CMML DTD, several parameter entities
      are defined that are used throughout the DTD as data types. This
      section gives a brief overview of them and refers to the
      relevant standards in which they are defined.
      </t>

      <section title="ContentType">
        <t>A "ContentType" specifies the media type and subtype of a
        document as defined in <xref target="ContentType">RFC
        2045</xref>. It is used to specify the type of content that
        one input time-continuous bitstream contains. Examples are
        "application/annodex", "audio/x-speex", "video/x-theora", or
        "video/mpeg".
        </t>
      </section>

      <section title="LinkTypes">
        <t>"LinkTypes" specifies a space-separated list of the types of
        relationships a linked, i.e. related, document has to the current
        one. As in XHTML, user agents, search engines, etc. may interpret
        these link types in a variety of ways. For example, user agents 
        may provide access to linked documents through a navigation bar.
        Authors may use the following recognized link types which are a
        superset of the ones used for XHTML/HTML:
          <list style="symbols">
            <t>edit: Refers to a document that allows editing the resource.
               This enables a document author to allow others to edit
               the CMML which is the basis for an Annodex resource.
            </t>
            <t>alternate: Designates substitute versions for the document
               in which the link occurs. When used together with the media
               attribute, it implies a version designed for a different 
               medium (or media).
            </t>
            <t>stylesheet: Refers to an external style sheet.
            </t>
            <t>start: Refers to the first document in a collection of 
               documents. This link type tells search engines which document
               is considered by the author to be the starting point of the
               collection.
            </t>
            <t>next: Refers to the next document in a linear sequence of
               documents. User agents may choose to pre-load the "next" 
               document, to reduce the perceived load time.
            </t>
            <t>prev: Refers to the previous document in an ordered series of
               documents.
            </t>                
            <t>contents: Refers to a document serving as a table of contents.
               Although this may seem strange in a CMML file, it makes sense
               in an Annodex file and may simply refer back to the CMML file
               or to a HTML page that provides similar information.
            </t>
            <t>index: Refers to a document providing an index for the current
               document.
            </t>
            <t>glossary: Refers to a document providing a glossary of terms 
               that pertain to the current document.
            </t>
            <t>copyright: Refers to a copyright statement for the current
               document. While this could also be given in the meta tags,
               this could refer to a formatted, legal document.
            </t>
            <t>chapter: Refers to a document serving as a chapter in a 
               collection of documents.
            </t>
            <t>section: Refers to a document serving as a section in a 
               collection of documents.
            </t>
            <t>subsection: Refers to a document serving as a subsection in a 
               collection of documents.
            </t>
            <t>appendix: Refers to a document serving as an appendix in a 
               collection of documents.
            </t>
            <t>help: Refers to a document offering help (more information, 
               links to other sources information, etc.)
            </t>
            <t>bookmark: Refers to a bookmark. A bookmark is a link to a key
               entry point within an extended document. The title attribute may
               be used, for example, to label the bookmark. Note that several
               bookmarks may be defined in each document.
            </t>
          </list> 
        </t>
      </section>

<!-- IS DISCOURAGED IN XHTML, SO LET'S NOT START BAD STYLE
      <section title="StyleProperties">
        <t>A "StyleProperties" specifies style properties to be used for
           this element. This is used for the style attribute, which
           specifieds style information for the current element.
           In XHMTL the use of the style attribute is strongly discouraged
           in favor of the style element and external style sheets. Small 
           devices don't generally support these in-line styles.
        </t>
      </section>
-->

      <section title="MediaDesc">
        <t>A "MediaDesc" describes one or several types of devices for 
        which the given style is appropriate. It is given as a list of
        comma-separated media descriptors. Which devices are supported
        will need to be specified in a separate style sheet specification.
        The following set of device types, adapted from XHTML/HTML
        in CSS1, are recognized:
          <list style="symbols">
            <t>all: suitable for all devices.
            </t>
            <t>aural: suitable for speech synthesizers.
            </t>
            <t>braille: intended for braille tactile feedback devices.
            </t>
            <t>embossed: intended for paged braille printers.
            </t>
            <t>handheld: intended for handheld devices (characterized
            by a small, monochrome or colour display and limited bandwidth).
            </t>
            <t>print: intended for paged output to a printer or print
            preview on a screen.
            </t>
            <t>projection: intended for projected presentations (projectors
            or print to transparencies).
            </t>
            <t>screen: intended for non-paged, colour computer screens.
            </t>
            <t>tty: intended for fixed-pitch character grid displays (such
            as the teletypes or terminals).
            </t>
            <t>tv: for television-type devices with low resolution and
            limited scrollability.
            </t>
          </list> 
        </t>
      </section>

      <section title="Text">
        <t>A "Text" describes a short, free form text being used for
        the "title" attribute.
        </t>
      </section>

      <section title="URI">
        <t>A "URI" is a character string that conforms to the
        specification of the Uniform Resource Identifier as defined in
        <xref target="URI">RFC 3986</xref>. A URI generally points to
        a Web resource.  The <xref target="timedURI">URI time interval
        specification</xref> is supported for CMML and Annodex
        files. Also, direct addressing of clips as specified in the
        MIME type application part of this document is supported for
        CMML and Anndex files.
        </t>
      </section>

      <section title="LanguageCode">
        <t>The "LanguageCode" defines a collection of constant strings
        that each identify a specific language as defined in <xref
        target="LANG">RFC 1766</xref>. Examples are: en-au, de, x-klingon.
        Language codes are used to provide internationalisation support. 
        </t>
      </section>

      <section title="Internationalisation support">
        <t>To provide international language support, the i18n entity
        draws together a language given by a "LanguageCode" in "lang"
        with the directionality of that language in "dir" given either
        as ltr (left-to-right) or rtl (right-to-left).  "ltr" is the
        default.
        </t>
      </section>

      <section title="Time specifications">
        <t>There are three different time specifications in use in
        CMML: "Timestamp", "Playbacktime" and "UTCtime".
        </t>

        <t>A "Timestamp" is generally a name-value pair which defines
        a time point. The time point value is interpreted according to
        the time scheme given in the name. If the name is ommitted, it
        defaults to "npt:". Valid time schemes are the ones defined in
        the <xref target="timedURI">temporal URI specification</xref>.
        </t>

        <t>The "Playbacktime" entity is a data type that just
        specifies a SMPTE or a NPT time. It is therefore equal to the
        Timestamp entity without the UTC specification.
        </t>

        <t>The "UTCtime" entity is a data type that just specifies a
        UTC time without an identifier. UTC time is specified as in
        the Timestamp entity, but without the "clock:" identifier.
        </t>
        
      </section>
      
      <section title="Core Attributes">
        <t>To cluster together the attributes that are common to
        most displayable elements, the "attrs" entity draws them together.
        As "i18n" is already a cluster, a "coreattrs" entity is defined,
        which groups together the other commonly used attributes for
        displayable elements, namely the unique identifier given in "id",
        the "class" attribute which provides a space-separated list of 
        style sheet classes that the element belongs to, and the "title" 
        attribute, which provides a short tooltip-like description 
        for an element.
        </t>
      </section>

    </section>

    
    <!--**************-->
    <!-- Root element -->
    <!--**************-->
    <section title="The preamble and the 'cmml' root element">
      
      <t>A CMML file is an XML instance document of the CMML DTD. An
      example is given in the Appendix. It starts with the usual xml
      directive and the DTD specification (see
      http://www.w3.org/TR/REC-xml#sec-prolog-dtd). The following is
      an example preamble:
      </t>

      <figure>
        <artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE cmml SYSTEM "cmml.dtd">
            ]]></artwork>
      </figure>

      <t>After the preamble, the CMML tag follows. A CMML file has a
      "cmml" tag as the root element. It embraces all the other tags.
      </t>
      
      <figure>
        <artwork><![CDATA[
<!ELEMENT cmml (stream?, head, clip*)>
<!ATTLIST cmml
  %i18n;
  id          ID             #IMPLIED
  xmlns       %URI;          #FIXED 'http://www.annodex.net/cmml'
  granulerate CDATA          #IMPLIED
  >
            ]]></artwork>
      </figure>

      <t>The "cmml" tag encloses at most one "stream" element, exactly
      one "head" element, and as many "clip" elements as the document
      author requires. A "clip" element describes a section of the
      related Annodex bitstream.
      </t>

      <t>Attributes of the "cmml" element are the usual xml root tag
      attributes: the internationalisation attributes "lang" and
      "dir", an identifier "id", a fixed namespace "xmlns", and the
      "granulerate".
      </t>

      <t>The internationalisation attributes specify the default
      language (language and directionality) of the complete CMML
      document. If not given, the language default adheres to the same
      rules as HTML, where the setting of the HTTP "Content-Language"
      header may specify the default language of a HTML document
      received over HTTP, or ultimately the user agent defaults and
      user preferences set the language. (see 
      http://www.w3.org/TR/REC-html40/struct/dirlang.html)
      </t>

      <t>Every element has an "id" attribute. The value of the "id"
      attribute MUST be unique within the document. It allows to
      uniquely identify an instance of an element and address it.
      </t>

      <t>The "granulerate" attribute may provide a base temporal resolution for
      the CMML bitstream. This is in particular used for creation of Annodex
      files from a given CMML instance document.
      </t>

    </section>
    
    
    <!--****************-->
    <!-- Stream element -->
    <!--****************-->
    <section title="The cmml 'stream' tag">

      <t>The "stream" element contains information that is used for
      authoring <xref target="ANX">Annodex</xref> bitstreams
      from existing time-continuous data. The Annodex bistream is
      created by multiplexing the bitstreams given in the "src"
      attributes of the "import" tags of the "stream" element together
      with the CMML annotations in a time-synchronous manner. 
      </t>

      <t>The "stream" element describes in the "import" tags the input
      time-continuous bitstreams that are to be multiplexed together on
      authoring the Annodex bitstream. Its attributes
      describe other features of the Annodex bitstream such as the
      time mappings for the start of the file.
      </t>

      <figure>
          <artwork><![CDATA[
<!ELEMENT stream (import*)>
<!ATTLIST stream
  id          ID             #IMPLIED
  basetime    %Playbacktime; "0"
  utc         %UTCtime;      #IMPLIED
  >
            ]]></artwork>
      </figure>

      <t>The "stream" element has no text attributes and thus
      internationalisation attributes are not required. The "id"
      attribute follows the default language specified in the "cmml"
      element.
      </t>

      <t>The "basetime" attribute contains a playback time in seconds
      associated with the first data packet of the Annodex
      bitstream. All other times in the CMML file MUST be calculated
      relative to this basetime. For example, a basetime of 300
      seconds npt for a video file implies that the first frame is
      related to a play time of 300 seconds, and a clip with a start
      time of 350 seconds is to be included 50 seconds into the
      Annodex bitstream.  If no basetime (or no stream tag) is given,
      the basetime defaults to 0 npt. The basetime can be given as a
      SMPTE or NPT time, or as a rational number as in 5/1300, but
      not as a utc time.
      </t>

      <t>The "utc" attribute associates a calendar date and a
      wall-clock time with the basetime. It therefore provides a
      mapping of the basetime to a real-world clock time and is given
      as a UTC time. If it is omitted, the start attribute in the
      import tag, and the start and end attributes in clip tags MUST
      NOT be specified as UTC times.
      </t>

      <t>The content model of the "stream" tag then proposes an
      arbitrary number of input bitstreams. These are described one by
      one in the "import" element.
      </t>

      <!--****************-->
      <!-- Import element -->
      <!--****************-->
      <section title="The 'import' tag">        

        <t>A "import" tag contains information on one of the input
        bitstreams for the multiplexing process. It may also contain
        additional parameters to set up the Annodex encoder for each
        import bitstream. 
        </t>

        <figure>
          <artwork><![CDATA[
<!ELEMENT import (param*)>
<!ATTLIST import
  %i18n;
  id          ID             #IMPLIED
  granulerate CDATA          #IMPLIED
  contenttype %ContentType;  #IMPLIED
  src         %URI;          #REQUIRED
  start       %Timestamp;    "0"
  end         %Timestamp;    #IMPLIED
  title       CDATA          #IMPLIED
  >
            ]]></artwork>
        </figure>

        <t>The relevant bitstream (fragment) is referenced through the
        "src" attribute. The src is a URI and may thus also contain a
        time interval specification in URIs which narrows down the
        input file to that given subpart. That resource is multiplexed
        into the Annodex bitstream starting at the time given
        in the "start" attribute and ending at the latest at the time
        given in the "end" attribute. The "start" and "end" attributes
        are interpreted relative to the timeline of the Annodex bitstream.
        </t>
        
        <t>The internationalisation attributes provide the language of
        the import element's and the contained param tags' attribute
        values, such as the "id" attributes and the "title" attribute.
        </t>

        <t>The "granulerate" attribute contains the base temporal
        resolution in Hz of the input bitstream referred in the "src"
        attribute. It depends on the encoding format of the input
        bitstream and typically contains the framerate for video
        (e.g. 25 frames/sec) and the samplerate for audio (e.g. 44100
        samples/sec), but may contain any rational number given with
        an integer denominator larger than 1 sec (e.g. 25 frames on 2
        seconds). Each bitstream has its own granulerate dependent on
        its specific encoding. This attribute is implied as it can be
        determined automatically during the multiplexing process from
        the headers of the encoded media bitstream. For bitstreams
        without header, such as uncompressed audio, the author of the
        CMML file can provide the granulerate to the multiplexer in
        this attribute.
        </t>

        <t>The "contenttype" attribute specifies the <xref
        target="ContentType">media type</xref> of the input bitstream
        referred in the "src" attribute. It is optional as the media
        type can often be derived from the file name or file header of
        the media source during multiplexing.
        </t>

        <t>The "src" attribute specifies a URI to the input
        bitstream. Commonly used URI schemes are "file" and "http".
        For specifying temporal subsets of the input bitstream, use
        the <xref target="timedURI">time interval specification for
        URIs</xref>.
        </t>

        <t>The "start" attribute specifies a time in the output
        Annodex bitstream at which the media bitstream will be
        inserted. This time is specified with respect to the
        "basetime" attribute given in the "stream" element.
        </t>

        <t>The "end" attribute specifies a time in the output Annodex
        bitstream at which the media bitstream will stop at the
        latest. This time is also specified with respect to the
        "basetime" attribute given in the "stream" element. This
        attribute is not required when the full bitstream is used.
        </t>

        <t>The optional "title" attribute provides a chance to jot
        down a human readable comment on the source bitstream. This
        may e.g. be used in authoring applications for a more human
        readable display than the "id" tag which is really a key for
        identifying elements uniquely.
        </t>

        <t>The content model of the "import" tag then allows an
        arbitrary number of "param" tags to add as many descriptive
        parameter values to the mulitplexing activity as necessary.
        </t>

      </section> <!--import-->
      
      <!--****************-->
      <!-- Param element -->
      <!--****************-->
      <section title="The 'param' tag">        
          
        <t>A "param" tag is empty, but its attributes contain a
        name-value pair for describing the input bitstream in the
        parent "import" element. It inherits its internationalisation
        from that element, too, to avoid overhead. The "param" element
        is declared as follows:
        </t>
          
        <figure>
            <artwork><![CDATA[
<!ELEMENT param EMPTY>
<!ATTLIST param
  id          ID             #IMPLIED
  name        CDATA          #REQUIRED
  value       CDATA          #REQUIRED
  >
            ]]></artwork>
        </figure>

        <t>The "name" attribute identifies a property name. It does
        not list legal values for this attribute.
        </t>
        
        <t>The "value" attribute specifies a property's value. It does
        not list legal values for this attribute.
        </t>
          
        <t>An example parametrisation is the provision of
        machine-processable low level meta information about the import
        bitstream such as a video's image height and width and framerate.
        </t>
          
      </section> <!--param-->
      
    </section> <!--stream-->
    
    
    <!--**************-->
    <!-- Head element -->
    <!--**************-->
    <section title="The cmml 'head' element">

      <t>The CMML "head" element contains annotation information on
      the complete Annodex bitstream, for whose creation the CMML file
      is used. It therefore contains header-type information such as a
      title, style information, related documents and meta information
      describing the bitstream.
      </t>

      <t>The "head" element is declared as the following:
      </t>
        <figure>
          <artwork><![CDATA[
<!ENTITY % head.misc "(style|meta|link)*">

<!ELEMENT head (%head.misc;,
                ((title, %head.misc;, (base, %head.misc;)?) |
                (base, %head.misc;, (title, %head.misc;))))>
<!ATTLIST head
  %i18n;
  id          ID             #IMPLIED
  profile     %URI;          #IMPLIED
  >
            ]]></artwork>
        </figure>
        
      <t>The "head" tag must contain a "title" tag. It may contain one
      "base" tag before or after the "title" tag and any number of
      "style", "meta", or "link" tags at any position.
      </t>

      <t>The "%i18n;" attribute specifies the base language of the
      "head" tag's attribute values.
      </t>

      <t>The value of the "profile" attribute is a space-separated
      list of base URIs specifying locations of "meta" tag schemes
      such as the Dublin Core (see http://dublincore.org/). These
      schemes may be used in the "meta" elements of the "head" or the
      "clip" tags.
      </t>
        
      <!--***************-->
      <!-- Title element -->
      <!--***************-->
      <section title="The 'title' element">
        
        <t>The "title" tag gives a descriptive title for the complete
        Annodex bitstream. It is not considered to be part of the
        presentation and should be displayed, e.g. as the title of the
        window that the Annodex bitstream is being displayed in.
        Exactly one title is required per document.
        The "title" element is declared as the
        following:
        </t>
        <figure>
          <artwork><![CDATA[
<!ELEMENT title (#PCDATA)>
<!ATTLIST title
  %i18n;
  id          ID       #IMPLIED
>
            ]]></artwork>
        </figure>

        <t>The "%i18n;" attribute specifies the base language of the
        "title" text.
        </t>
 
      </section>

      <!--**************-->
      <!-- Base element -->
      <!--**************-->
      <section title="The 'base' element">
        
        <t>The "base" element defines the base URI of the Annodex
        bitstream. All relative URIs of the bitstream get interpreted
        relative to this base.  The "base" element is empty, but its
        attributes contain the base URI.  It is declared as follows:
        </t>

        <figure>
          <artwork><![CDATA[
<!ELEMENT base EMPTY>
<!ATTLIST base
  id      ID       #IMPLIED
  href    %URI;    #REQUIRED
>
            ]]></artwork>
        </figure>
        
        <t>The "href" attribute contains the base URI. If the "base"
        element is omitted, the base URI of the Annodex bitstream is
        derived from the address through which the Annodex bitstream
        is accessed.
        </t>
        
      </section>
      
      
      <!--**************-->
      <!-- Meta element -->
      <!--**************-->
      <section title="The 'meta' element">
        
        <t>The "meta" element in the "head" element defines structured
        annotations for the complete Annodex bitstream. A "meta"
        element is empty, but its attributes contain the name-value
        pairs of a structured annotation. The "meta" element is
        declared as follows:
        </t>
        <figure>
          <artwork><![CDATA[
<!ELEMENT meta EMPTY>
<!ATTLIST meta
  %i18n;
  id       ID       #IMPLIED
  name     NMTOKEN  #IMPLIED
  content  CDATA    #REQUIRED
  scheme   CDATA    #IMPLIED
>
            ]]></artwork>
        </figure>

        <t>The "%i18n;" attribute specifies the language of the meta
        attribute and content texts.
        </t>

        <t>The "name" attribute identifies a property name. It does
        not list legal values for this attribute.
        </t>