Complex sentence: Cougar is a Sandia Labs and University of New Mexico collaboration; it is a lightweight OS based on PUMA, a system that was also designed for use on the Paragon supercomputer.
Split into simpler sentences: Cougar is a Sandia Labs and University of New Mexico collaboration. Essentially, it is a lightweight OS based on PUMA, a system that was also designed for use on the Paragon supercomputer.