Subject Re: [firebird-support] DDL for graph edges
Author Doug Chamberlin
Michael, et al:

This recent article on conceptual data modeling might be a fun read for you.

Since it focuses on the conceptual level, it may be seen as a bit off
topic for the support list but I like to bring the conceptual level all
the way down to the logical and physical because it helps everyone keep
things well organized. That makes it on topic in my book.