[tei-council] @scheme datatype

[Lou Burnard]

The scheme attribute is variously used with more or less the same 
semantics  to give a short name for some external classification 
scheme,  values from which are being deployed in a TEI document

It has the datatype  data.pointer on <keywords>, <classCode>, <catRef>, 
<occupation> and <socecStatus>, and the datatype data.enumerated on 
<locus>, <att>, <gi>,<tag>

This inconsistency seems undesirable. Changing them all to data.pointer 
means that they can provide URLs for the schemes concerned which seems 
more useful than encouraging people to go on using arbitrary opaque 
codes like "LCSH" (for which now read http://classificationweb.net).

Dissenters please speak up!