Interesting. I used to be a Windchill admin but never dealt with .ol as I never bothered to unzip a .pvz file and see what was inside.
Based on the Help, it sounds like an intermediate format. I don't know why your supplier would send you that. Part of the viewable generation process is to ensure that it is one way. You can send someone a .pvs or .pvz viewable file, but then they cannot reverse engineer actual CAD from those files.