What exactly does "supports Linux" mean?

[Stephan von Krawczynski <skraw@ithnet.com>]

Dear all,

I recently came across a very annoying question regarding Linux compatibility.
It rises a fundamental question which should be discussed, IMHO. 
Facts are:
I bought a card from some vendor, claiming "support for Linux". I tried to make
it work in a configuration with a standard 2.4.20 kernel from kernel.org. The
drivers (kernel modules) are binary-only. They did not load because of a
version mismatch. Asking for versions loadable with standard kernels, I got the
response that they only support kernels from Red Hat and SuSE, but no standard
kernels.
This leads to my simple question: how can one claim his product supports linux,
if it does not work with a kernel.org kernel? Is there any paper or open
statement from big L (hello btw ;-) available what you have to do to call
yourself "supporting linux"?
I know that the technical background is ridiculous, because it should very well
be possible to recompile their drivers under stock 2.4.20, but it looks like
they don't want to, simply.
I am in fact a bit worried about this behaviour, because I take it as a first
step to a general market split up already known to *nix.
My general conclusion would be that something not working with a standard
kernel cannot be called "supporting linux", no matter what distros ever are
supported. You may call me purist...
Any ideas?

Regards,
Stephan