Entity Relationship Diagram - ISA direction

Question

In ERD I am used to see something like:

But I ran into some cases where the triangle is upsidedown, like:

So I wondered, does the direction of the ISA triangle matters? It seems only logical that the pointy vertex would point at the parent, and inheritants would go from the edge itself.

Answer 1

There's no inherent meaning in the orientation of the triangle. In your examples, they mean exactly the same thing. Different tools might implement it differently, and there are other conventions for subtyping besides triangles.

I suggest you pick the more popular convention and stick with it.