Enhanced Entity Relationship Diagram question

Currently creating a EERD diagram for a university assignment.

I've pretty much finished it, and decided to have a quick browse around the internet to make sure I've set it out correctly etc. (Although I'm aware some people take up various notations)

I've created mine with no Primary keys and foreign keys in my subclasses, because the subclass entity inherits the PK from the superclass.

And the reason I haven't put in any foreign keys is that my understanding was the relationships in the diagram then become the foreign keys at the development stage.

I've found a few diagrams that put new PKs in subclass entities and foreign keys without naming any relations.

Should I continue as I've done it?

On a side note - whats the best piece of software to draw my EERD?

Cheers guys.

i've been doing ERDs for decades, and have never heard of subclasses

on the other hand, every ERD i've ever worked with has always shown both PKs and FKs

good luck with your assignment

Its an Enhanced Entity relationship diagram.

So I've used Specialization and generalization.

Just incase I explained it wrong