> Is there something like the Language Reference for Intebase 6.0 for
> Interbase up to 1.5?
> Or do i have to get the required information out of the Release Notes
> for FB?

There is the InterBase 6.0 Beta documentation set at
IBPhoenix available, but if you are planning to use
Firebird frequently, then I would highly recommend
to spend some bucks and order the IBPhoenix CD.
http://www.ibphoenix.com/main.nfs?a=ibphoenix&s=1074351601:3040&page=ibp_cd

On the CD there are 2 real Firebird manuals included.

Combined with the actual Firebird 1.5 Release Notes,
that is everything you need.

HTH,
Thomas