Hi all,

I'm sure this has been discussed before, but I couldn't find it...

I want to add user-generated tags into a DC record/description set (within an Application Profile).  I want to be able to differentiate them from "authoritative" values in the record.

There are two questions:

1. Is a tag a dc:subject or a dc:description.  I'm guessing dc:description, since you can't guarantee a tag is a "topic of the resource" - it might be a type, creator, language, coverage, etc.  The other alternative is it just doesn't fit within any of the existing DCMI terms so needs to be a new stand-alone property?

2. Assuming it's a dc:description, is it a sub-property or is it identifiable because it is a dc:description with a particular encoding scheme?  Though it's hard to think a "list of whatever words you can ever think of that might somehow relate to this described resource" could be considered a vocabulary encoding scheme ("an enumerated set of resources").  And there isn't really a syntax that could be specified either, as a tag is basically a free-text literal string.

My inclination is to define a new property that is a sub-property of dc:description ("an account of the resource"), called "tag" that is a literal string.  I guess I'll need to find my own namespace for it.

eg.
<ex:tag>FavouriteStuff</ex:tag>

As an aside.  A nice extension would be to add the source of each tag (ie. which user created it).  DC records are silent on how this amassed set of property/value pairs came into being.  The Abstract Model allows you to specify how a literal string is structured or what list it is a member of, but not where it came from (ie. who said so).  There is Admin Core floating around, I guess this could be added to the sub-description of each tag?  

eg.
<ex:tag rdf:parseType="Resource">
  <rdf:value>FavouriteStuff</rdf:value>
  <ac:source>jonjon</ac:source>
</ex:tag>

Or, is it too much of a stretch to say each user defines/creates a vocabulary, so therefore this tag is from their vocabulary?

eg.
<ex:tag rdf:parseType="Resource">
  <dcam:memberOf rdf:resource="http://example.com/user/jonjon/tags/" />
  <rdf:value>FavouriteStuff</rdf:value>
</ex:tag>

Thanx,
Douglas
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