Some times not fully compatible and when I have
application (full tested and work correctly} I
can't switch the gds32.dll for next IB server (I install new one),
I must tests application again -> hard to install
new app.

Slavek

>For work with diferent version of IB server is usualy needed
>diferent version of clients library (gds32.dll under windows).

Why? AFAIK any client library can work with any IB server.
API is also compatible. Of course, applications using a new
extensions of API can't work with an old gds32.dll, but it is not
a problem because old applications can work with a new
gds32.dll.