+ Free Format data model fields and extensibility mechanism
When a data provider cannot use the proposed value fields (for instance in data product type), how can he/she still provide some information to characterise his/her data sets?
 
-  How could we allow for extensibility?  If we need to consider new kinds of science data product , not yet defined in the ObsTAP fields , how should we proceed?
-  Description of a data set - obs_title. In ObsTAP , it is not a mandatory field, it could become important in future releases if its usage is well-defined. At the moment it is just free-format, and that could be an issue.
Regarding extensibility, I think we should take the advice of 
MarkusDemleitner regarding 
DataProduct, and have the values added as IVOA-controlled and registered enumerations. If possible, both a hierarchical and yuxtapositional notation (à la UCD) should be used.
Regarding 
obs_title, I do not think we should rely on it for discovery. We should try to push for 
obs_creator_did, or at least for 
obs_publisher_did, as the ways for PIs to refer to VO datasets in their literature. Conversely, use of bib_reference should be allowed for discovery, and substituted by a VARCHAR(19) (length of a bibcode), or bigger if DOIs where to be allowed (something like VARCHAR(2048) should cover most ground for existing DOIs. 
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JuanDeDiosSantanderVela - 07 Mar 2011
As far as I understand obs_title is a free text description. Maybe usefull but the field name is confusing I think. Nothing to do with 
an ID.
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FrancoisBonnarel - 15 Mar 2011