Ok, I think I understand.

So the Version and VersionIndependentProgID nodes are used to indicate
versions of the DLL?

Also, one other thing. In this line:

IMPLEMENTS _dzactxEvents IN {0E9D0E41-7AB8-11D1-9400-00A0248F2EF0}#1.0

I don't understand the use of the registry key. Does this mean that the
registry key here is the same always on all PC's? Also, why use the
registry key value; why can't we use:

IMPLEMENTS _dzactxEvents IN dzactx.dll


Thanks.