OSS required?

Hello all:
   I have just checked out a copy of the cvs repository.
I plan to get the software built and running on OpenBSD 
3.2-current machines of various architectures.  I have 
noticed in output.c a #include for a system level header 
<sys/souncard.h> this seems to be part of the OSS system 
(by 4front?) I am currious if this API subsystem is 
required by octal or if this is optional.  Does this 
software depend on software that isnt free?  Anyway, I was 
just currious and thought I would ask the people who know. 
 Have a good day.

-roman