content, format, ctype, or xtype ?

[Rob Seaman]

Roy Williams wrote:

> Can't we bring TAP back to its original limited purpose as an  
> interface to a database?

The nature of an interface is to tie two things together.  In this  
case, Roy reminds us that on one side lie tables in a DB.  On the  
other side are VO users.  Presumably there is a list of table-access  
use cases that TAP is intended to address?

How will users benefit from having TAP?  What specifically will  
applications do with all these meta-metadata tags?  Assume the DM and  
representational hooks are indeed carried in some fashion from point A  
to point B.  To what purpose will they be put?  Or rather, will most  
of the knowledge of the underlying tables be built into the purpose- 
built applications anyway?

For instance, a typical VOish answer might be that a meta^2data rich  
TAP will permit joins between foreign tables created (very, very  
carefully created) by different institutions for different purposes.   
Do we have specific such examples in mind?  How do such use cases flow  
down to the details of specifying [c|x|u]types?

Rob