Hi Dojo
I have a device with 5 codecs. Each with some settings that are displayed in a table. I want to have the unit name in the display key in all of these tables, so a foreign key is needed to the connections table. Since they all share the same primary key i wondered if that could be used as a primary key.
I tried it out and defined a relation between the security table and the connections table, with the primary key of the security table as foreign key and defined the naming format to use the unit name of the connections table to build the display key. This seems to work, DIS doesn't flag it as an issue bit the table editor does. What are the guidelines on this? 
Hi Arne
The documentation (at the bottom) also mentions to not specify the FK on the index as this could not work: Foreign keys | DataMiner Docs
Even though it works for you now, won't mean that it will continue to work. This is currently undefined behavior and is not supported.