Parx was a french dealer for ATARI programs.
M&E (Modulaire et Evolutif - Modular and Evolutive) is a concept build by Parx to make some standards on software plugins.
Mem manager stand for memory manager. Parx softwares store their plugins into dedicated folders. I Suppose Parx.sys is the name of one of them.
Try Rodolphe Czuba's web site :
http://www.czuba-tech.com/
Rodolphe Czuba did work with Parx and made some Parx software updates after Parx ended (1997 or 1998).
You may send him an email there if nobody else give you a better answear than mine.
If no more answear come from this forum or from Rodolphe, post a new message here. I will try to get you more informations from someone else if I could.