From the 2018-10-12 SST meeting; freeform notes in an old version of the DPDD document mentioned the "Issue of adding Sources, like DIAObjects, to the Object list". This was discussed at an earlier DMLT in Tucson. The notes state: "People requested a more automatic join from objects and sources. Wanted to derive objects by associating them with sources? Jim and Robert are not keen on doing this. "
Zeljko Ivezic to check in his notes