Appendix C History
In March of 2001, Tom Impelluso started a thread on the history of OpenGL. In the near future, I will write this into a more formal FAQ article. In the meantime, you can review the thread through March 8th, 2001.
Allen Akin, who has been both a manager of a PEX development group at DEC and of an OpenGL development group at SGI, contributed his historic whitepaper to this FAQ, which compares the two APIs: Analysis of PEX 5.1 and OpenGL 1.0 from SIGGRAPH 1992.