[topicmapmail] Why do we need <subjectIdentity> for Published Subjects?

[Marc de Graauw]

Why exactly do we need the construct <subjectIdentity><subjectIndicatorRef 
.../></subjectIdentity> for Published Subjects? Can't we achieve exactly the 
same thing using scope, a name and the Topic Naming Constraint?

Example using <subjectIdentity> (from XTM1.0):

	<topic id="dutch">
		<subjectIdentity>
			<subjectIndicatorRef 
xlink:href="http://www.topicmaps.org/xtm/1.0/language.xtm#nl"/>
		</subjectIdentity>
		<baseName>
			<baseNameString>Dutch</baseNameString>
		</baseName>
	</topic>

Example using scope and name:

	<topic id="dutch">
		<baseName>
			<scope>
				<subjectIndicatorRef 
xlink:href="http://www.topicmaps.org/xtm/1.0/language.xtm"/>
			</scope>
			<baseNameString>nl</baseNameString>
		</baseName>
		<baseName>
			<baseNameString>Dutch</baseNameString>
		</baseName>
	</topic>

This looks equivalent to me to saying: we have a controlled vocabulary with 
unique names. The scope of the first basename is this controlled vocabulary 
(http://www.topicmaps.org/xtm/1.0/language.xtm), the basenamestring is one of 
the unique names (nl) from this vocabulary. If the controlled vocabulary is 
published, it's a Published Vocabulary. Doesn't that achieve the same effect 
that <subjectIdentity> in the first example does? The TNC would force merging 
with:

	<topic id="nederlands">
		<baseName>
			<scope>
				<subjectIndicatorRef 
xlink:href="http://www.topicmaps.org/xtm/1.0/language.xtm"/>
			</scope>
			<baseNameString>nl</baseNameString>
		</baseName>
		<baseName>
			<baseNameString>Nederlands</baseNameString>
		</baseName>
	</topic>

So are these just two different syntactical ways to achieve the same semantical 
effect, or am I missing some profound difference between both examples?

Marc

P.S.: I know the TNC is under discussion, but let's assume for the sake of this 
argument that the TNC is retained. It is after all part of 13250 and XTM.