ER Relationship Class Hierarchies missing?

[Genadi Saltikov <carmageddon gmail com>]

I am continue to investigate using Dia for ERD designs.

Now I have stumbled across the ER charts missing the inheritance functionality, denoted by "ISA" which is a triangle pointing upwards, connecting between something like "Employee" entity  and inheriting entities such as "Hourly Employee" and "Contract Employee".

So, please tell me I missed something, and there is a way to do those ER things in Dia :)

Thanks!