However, that only seems to handle relationships between arcs and vertices. Do I do the same for Column C - for relationships between arcs and arcs?
Yes
Also, is there any shortcut to say (for example) from any relationship to any other relationship, this relationship is allowed?
No. For diagram objects you can use @Element to include anything derived from UML::Element, i.e. everything, but link:@Element hasn't been implemented yet.
Also the value after the link: value needs to be the type of the relationship, yes? The stereotype will provide the metatype definition.
Yes. There is a list in the help.
Shouldn't there be
link:@Relationship as well to allow any relationship? (As per my original question above). I am assuming
link:@Element is used for relationships from relationships to elements - or have I misunderstood?
BTW, is @Element implemented now (v134)? So I could set up some generic relationships?
I tried to define a derivation relationship between two InformationFlows:
link:InformationFlow,Flow,link:InformationFlow,Flow,link:InformationFlow,Flow,Abstraction,Drvtn,to,derives from,derives from,True,True,,True,ZZZZ,0,,,,,

When I try to QuickLink two such InformationFlows, nothing pops up (only the defaults). Have I set it up correctly?
Could you supply one "you prepared earlier"

So I can check that all is OK in my MDG?
Thanks,
Paolo