Beef up the documentation on relationship handling.
We should also include the standard relationship definition tagging into the schema definition documentatio. I realize we are either inconsistently using relationships now or just not doing it at all in other instances, but the goal is to converge on the metadata technique. So it is better to document the desired stage and highlight the bits that are incomplete or inconsistent instead.
Hint: Use the documentation available in DES - contact @gehrmann