way to represent UCDs in model.

[pahjbo]

It would be nice to have a standard way to be able to tag an attribute (or whole Datatype perhaps) with a UCD - The MeasurementDM has done this with a constraint with the description element containing the UCD - however as the description element of a constraint is really not strongly typed (it is more or less only a human readable description of some constraint at the moment), it is difficult to create standard processing that could use this information.

It is arguable whether this is actually a constraint or more properly associated semantic information. It would however be easy (and backwards compatible) to create a specialised constraint to allow a statically typed UCD constraint.

[pahjbo]

have added explicit ucd element to attribute - though now beginning to feel that typed constraint might be better