What is a Zetec Blacktop, and are there other types?

Zetec Blacktop is the phase 3 engine and post mid-98 and has a black cam cover with Zetec 16v on it.

Prior to this were 2 silver tops with metal cam covers. One had DOHC 16v (Phase 1) and the other zetec 16v (Phase 2)on the cover.

http://www.zetecinside.com/xr2/stepbystep.htm