In the current ObsTAP proposal, em_min and em_max are nullable. What does that mean when any of them is NULL? If the service is registered, and specifies the corresponding bands in the VO Registry, it should use the bounds of those bands as em_min and em_max for all the collection, unless it can provide better bounding.

Therefore, I propose that em_min and em_max must not be NULL.

-- JuanDeDiosSantanderVela - 07 Mar 2011