+2  A: 
Tony Andrews
Ok, that makes sense. I also found something called arcs. Do arcs perform the same function as what you mentioned above?
vrish88
No, arcs represent alternative relationships - e.g. an ORDER LINE may be for purchase of a PRODUCT or for purchase of a SERVICE (but not both).
Tony Andrews
A: 

Note that if you're working in the Design Editor on the physical model, you have to implement as actual tables.

But take a look at the documentation for the Foreign Key property "Arc", which might help some. You can set it so that exactly 1 of several foreign keys can have a value.

For example, you might set up FK's from your supertype table to each subtype table. Then enforce that exactly one can have a value by using that property and generating the TAPI for the tables. (The drawback is that you'd have to insert the subtype information before the supertype.)

Jim Hudson