Xm is missing

Hello.
I have one problem.I’ve tried to compile OpenInventor and I’ve reicived error message
Xm/Xm.h is missing.Can you tell me where I can
download it?
Thanks.

You need a copy of X-Motif development headers and libraries

Thank you very much.

[This message has been edited by FoxDie (edited 02-24-2002).]