TS file format

<?xml version="1.0" encoding="utf-8"?>
<!--
 !
 ! Some notes to the XSD:
 !
 ! The location element is set as optional since it was introduced first in Qt 4.2.
 ! The userdata element is set as optional since it was introduced first in Qt 4.4.
 ! The vanished message type was introduced first in Qt 5.2.
 !
  -->
<xs:schema elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <!-- value contains decimal (e.g. 1000) or hex (e.g. x3e8) unicode encoding of one char -->
  <xs:element name="byte">
      <xs:complexType>
        <xs:attribute name="value" type="xs:string" use="required" />
      </xs:complexType>
    </xs:element>
  <!--
   ! Type used in order to escape byte entities not allowed in an xml document
   ! for instance, only #x9, #xA and #xD are allowed characters below #x20.
    -->
  <xs:complexType name="byte-type" mixed="true">
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element ref="byte" />
      </xs:choice>
  </xs:complexType>
  <!--
   ! extra-something should be described as extra-* but wildcard is not valid in XSD. No better solution found.
   ! extra elements may appear in TS and message elements. Each element may appear
   ! only once within each scope. The contents are preserved verbatim; any
   ! attributes are dropped. Currently recognized extra tags include:
   !   extra-po-msgid_plural, extra-po-old_msgid_plural
   !   extra-po-flags (comma-space separated list)
   !   extra-loc-layout_id
   !   extra-loc-feature
   !   extra-loc-blank
    -->
  <xs:element name="extra-something" type= "byte-type"/>
  <xs:element name="TS">
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="extra-something" />
        <xs:element minOccurs="0" maxOccurs="1" ref="dependencies" />
        <xs:choice minOccurs="1" maxOccurs="unbounded">
          <xs:element ref="context" />
          <xs:element ref="message" />
        </xs:choice>
      </xs:sequence>
      <xs:attribute name="version" type="xs:string" />
      <xs:attribute name="sourcelanguage" type="xs:string" />
      <xs:attribute name="language" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="context">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="name" />
        <xs:element minOccurs="0" maxOccurs="1" ref="comment" />
        <xs:element minOccurs="1" maxOccurs="unbounded" ref="message"/>
      </xs:sequence>
      <xs:attribute name="encoding" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="dependencies">
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="1" maxOccurs="unbounded" ref="dependency" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="dependency">
    <xs:complexType>
      <xs:attribute name="catalog" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="name" type= "byte-type"/>
  <!-- This is "disambiguation" in the (new) API, or "msgctxt" in gettext speak -->
  <xs:element name="comment" type= "byte-type"/>
  <!-- Previous content of comment (result of merge) -->
  <xs:element name="oldcomment" type= "byte-type"/>
  <!-- The real comment (added by developer/designer) -->
  <xs:element name="extracomment" type= "byte-type"/>
  <!-- Comment added by translator -->
  <xs:element name="translatorcomment" type= "byte-type"/>
  <xs:element name="message">
    <xs:complexType>
      <xs:sequence>
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="location" />
        <xs:element minOccurs="0" maxOccurs="1" ref="source" />
        <xs:element minOccurs="0" maxOccurs="1" ref="oldsource" />
        <xs:element minOccurs="0" maxOccurs="1" ref="comment" />
        <xs:element minOccurs="0" maxOccurs="1" ref="oldcomment" />
        <xs:element minOccurs="0" maxOccurs="1" ref="extracomment" />
        <xs:element minOccurs="0" maxOccurs="1" ref="translatorcomment" />
        <xs:element minOccurs="0" maxOccurs="1" ref="translation" />
        <xs:element minOccurs="0" maxOccurs="1" ref="userdata" />
        <xs:element minOccurs="0" maxOccurs="unbounded" ref="extra-something" />
      </xs:sequence>
      <xs:attribute name="id" type="xs:string" />
      <xs:attribute default="no" name="numerus">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="yes" />
            <xs:enumeration value="no" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <!--
   ! If the line is omitted, the location specifies only a file.
   !
   ! location supports relative specifications as well. Line numbers are
   ! relative (explicitly positive or negative) to the last reference to a
   ! given filename; each file starts with current line 0. If the filename
   ! is omitted, the "current" one is used. For the 1st location in a message,
   ! "current" is the filename used for the 1st location of the previous message.
   ! For subsequent locations, it is the filename used for the previous location.
   ! A single TS file has either all absolute or all relative locations.
    -->
  <xs:element name="location">
    <xs:complexType>
      <xs:attribute name="filename" type="xs:string" />
      <xs:attribute name="line" type="xs:string" />
    </xs:complexType>
  </xs:element>
  <xs:element name="source" type= "byte-type"/>
  <!-- Previous content of source (result of merge) -->
  <xs:element name="oldsource" type= "byte-type"/>
  <!--
   ! The following should really say one byte-type or several
   ! numerusform or lengthvariant elements.
    -->
  <xs:element name="translation">
    <xs:complexType mixed="true">
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element ref="byte" />
        <xs:element ref="numerusform" />
        <xs:element ref="lengthvariant" />
      </xs:choice>
      <!--
       ! If no type is set, the message is "finished".
       ! Length variants must be ordered by falling display length.
       ! variants may not be yes if the message has numerus yes.
        -->
      <xs:attribute name="type">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="unfinished" />
            <xs:enumeration value="vanished" />
            <xs:enumeration value="obsolete" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
      <xs:attribute default="no" name="variants">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="yes" />
            <xs:enumeration value="no" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <!-- Deprecated. Use extra-something -->
  <xs:element name="userdata" type="xs:string" />
  <!--
   ! The following should really say one byte-type or several
   ! lengthvariant elements.
   ! Length variants must be ordered by falling display length.
    -->
  <xs:element name="numerusform">
    <xs:complexType mixed="true">
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element ref="byte" />
        <xs:element ref="lengthvariant" />
      </xs:choice>
      <xs:attribute default="no" name="variants">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="yes" />
            <xs:enumeration value="no" />
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:complexType>
  </xs:element>
  <xs:element name="lengthvariant" type= "byte-type"/>