multiple block data files (.bdf)

with the graphical edititor you have to start from the bottom up. You create a bdf, then go

file -> create/update -> symbol file for current file

This will create a .bsf file and add it to your current project that will allow you to place the symbol in another bdf. You can do this for as many levels of heiracrchy as you want (I have old designs that go through about 10 layers of BDF).

Be warned, until you try and synthesise the design it may not fully understand the heirarchy and might not open the other bdf when you click on the symbol in the higher level. But it definatly works because ive done it and we have plenty of designs that do it.