So a little history for your knowledge.
PBS was originally developed for NASA under a contract project. Altair Engineering acquired the rights to all the PBS technology and intellectual property from Veridian in 2003. Altair Engineering currently owns and maintains the intellectual property associated with PBS, and also employs the original development team from NASA.
The following versions of PBS are currently available:
OpenPBS — original open source version released by MRJ in 1998 (not actively developed)
TORQUE — a fork of OpenPBS that is maintained by Adaptive Computing Enterprises, Inc. (formerly Cluster Resources, Inc.)
PBS Professional (PBS Pro) — the version of PBS offered by Altair Engineering that is dual licensed under an open source and a commercial license.
PBS Professional has a more modern language specification for job submission, which is called select/place. If using PBS Professional, I would suggest using queuejob hook to evaluate the user’s job submission and modify the select/place requirements to meet your combination check.