title: How to show composite keys in Chen E-R Diagram
body: <p>How to show composite keys in Chen E-R Diagram? I have not used this notation and I really don't like it. Any references would suffice, as I have excellent understanding of data modeling concepts (what a brag!).
  Note: I am aware of the symbol for associative entity, in such a symbol, one may have an auto-increment key as the PK, but then again, one may use the 2 FKs. In the later case, the PK would be composite. I don't know how to show it since Chen attribute symbol is an oval for each attribute.
  Thanks.</p>