Merge pull request #335 from w3c/issue-0319-remove-position-on-tt

Remove support for tts:position on root (tt) element (#319).

spec/ttml2.xml

@@ -5388,7 +5388,6 @@ zero or one <el>body</el> element.</p>
 &lt;tt
   <loc href="#content-attribute-condition">condition</loc> = <loc href="#content-value-condition">&lt;condition&gt;</loc>
   <loc href="#style-attribute-extent">tts:extent</loc> = <loc href="http://www.w3.org/TR/xmlschema-2/#string">xsd:string</loc>
-  <loc href="#style-attribute-position">tts:position</loc> = <loc href="http://www.w3.org/TR/xmlschema-2/#string">xsd:string</loc>
   <loc href="#content-attribute-xml-id">xml:id</loc> = ID
   <loc href="#content-attribute-xml-lang"><phrase role="reqattr">xml:lang</phrase></loc> = <loc href="http://www.w3.org/TR/xmlschema-2/#string">xsd:string</loc>
   <loc href="#content-attribute-xml-space">xml:space</loc> = (<emph>default</emph>|<emph>preserve</emph>) : default
@@ -5426,10 +5425,7 @@ in an external namespace, such as <att>m708:aspectRatio</att> as defined in <bib
 This would permit, for example, the interchange of information that reflects
 the semantics of <bibref ref="cta708e"/> , &sect;4.5 “Caption Service Metadata”, “ASPECT RATIO”.</p>
 </note>
-<p>If the <loc href="#style-attribute-position"><att>tts:position</att></loc> attribute is specified on the <el>tt</el>
-element, then it must adhere to <specref ref="style-attribute-position"/>, in which case it
-specifies the position of the <loc href="#terms-root-container-region">root container region</loc> relative to a reference positioning rectangle.</p>
-<p>Except for the <att>tts:extent</att> and <att>tts:position</att> attributes described above, an attribute in the TT Style Namespace should not
+<p>Except for the <att>tts:extent</att> attribute described above, an attribute in the TT Style Namespace should not
 be specified on the <el>tt</el> element unless it denotes an inheritable style property, in which case such inheritable style property is available
 for <loc href="#semantics-style-inheritance-root">root style inheritance</loc>. If a non-inheritable style property is specified, then
 it must be ignored for the purpose of non-validation processing. In the case of validation
@@ -11089,7 +11085,6 @@ as a style property only to those element types indicated in the following table
 <tr>
 <td><emph>Applies to:</emph></td>
 <td>
-<loc href="#document-structure-vocabulary-tt"><el>tt</el></loc>,
 <loc href="#content-vocabulary-div"><el>div</el></loc>,
 <loc href="#content-vocabulary-p"><el>p</el></loc>,
 <loc href="#layout-vocabulary-region"><el>region</el></loc>