    <!--

    SSML DTD (20031204)

    Copyright 1998-2003 W3C (MIT, ERCIM, Keio), All Rights Reserved.

    Permission to use, copy, modify and distribute the SSML DTD and
    its accompanying documentation for any purpose and without fee is
    hereby granted in perpetuity, provided that the above copyright
    notice and this paragraph appear in all copies.

    The copyright holders make no representation about the suitability
    of the DTD for any purpose. It is provided "as is" without expressed
    or implied warranty.

    -->

    <!ENTITY % duration "CDATA">
    <!ENTITY % integer "CDATA">
    <!ENTITY % uri "CDATA">
    <!ENTITY % audio "#PCDATA | audio ">
    <!ENTITY % structure " p | s">
    <!ENTITY % sentence-elements " break | emphasis | mark | phoneme | prosody | say-as | voice | sub ">
    <!ENTITY % allowed-within-sentence " %audio; | %sentence-elements; ">

    <!ELEMENT speak (%allowed-within-sentence; | %structure; | lexicon | metadata | meta)*>
    <!ATTLIST speak
    	version NMTOKEN #REQUIRED
    	xml:lang NMTOKEN #REQUIRED
    	xmlns CDATA #FIXED 'http://www.w3.org/2001/10/synthesis'
    	xmlns:xsi CDATA #IMPLIED
    	xsi:schemaLocation CDATA #IMPLIED
            xml:base %uri; #IMPLIED
    >

    <!ELEMENT p (%allowed-within-sentence; | s)*>
    <!ATTLIST p
    	xml:lang NMTOKEN #IMPLIED
    >

    <!ELEMENT s (%allowed-within-sentence;)*>
    <!ATTLIST s
    	xml:lang NMTOKEN #IMPLIED
    >

    <!ELEMENT voice (%allowed-within-sentence; | %structure;)*>
    <!ATTLIST voice
    	xml:lang NMTOKEN #IMPLIED
    	gender (male | female | neutral) #IMPLIED
    	age %integer; #IMPLIED
    	variant %integer; #IMPLIED
    	name CDATA #IMPLIED
    >
    <!ELEMENT prosody (%allowed-within-sentence; | %structure;)*>
    <!ATTLIST prosody
    	pitch CDATA #IMPLIED
    	contour CDATA #IMPLIED
    	range CDATA #IMPLIED
    	rate CDATA #IMPLIED
    	duration %duration; #IMPLIED
    	volume CDATA #IMPLIED
    >
    <!ELEMENT audio (%allowed-within-sentence; | %structure; | desc)*>
    <!ATTLIST audio
    	src %uri; #REQUIRED
    >

    <!ELEMENT desc (#PCDATA)>
    <!ATTLIST desc
    	xml:lang NMTOKEN #IMPLIED
    >

    <!ELEMENT emphasis (%allowed-within-sentence;)*>
    <!ATTLIST emphasis
    	level (strong | moderate | none | reduced) "moderate"
    >

    <!ELEMENT say-as (#PCDATA)>
    <!ATTLIST say-as
    	interpret-as NMTOKEN #REQUIRED
    	format NMTOKEN #IMPLIED
    	detail NMTOKEN #IMPLIED
    >
    <!ELEMENT sub (#PCDATA)>
    <!ATTLIST sub
    	alias CDATA #REQUIRED
    >
    <!ELEMENT phoneme (#PCDATA)>
    <!ATTLIST phoneme
    	ph CDATA #REQUIRED
    	alphabet CDATA #IMPLIED
    >
    <!ELEMENT break EMPTY>
    <!ATTLIST break
    	time CDATA #IMPLIED
    	strength  (none | x-weak | weak  | medium | strong | x-strong) "medium"
    >
    <!ELEMENT mark EMPTY>
    <!ATTLIST mark
    	name CDATA #REQUIRED
    >

    <!ELEMENT lexicon EMPTY>
    <!ATTLIST lexicon
        uri %uri; #REQUIRED
        type CDATA #IMPLIED
    >

    <!ELEMENT metadata ANY>

    <!ELEMENT meta EMPTY>
    <!ATTLIST meta
    	name NMTOKEN #IMPLIED
    	content CDATA #REQUIRED
    	http-equiv NMTOKEN #IMPLIED
    >