What does PEX stand for?

What does PEX mean?

PEX	Cross-linked PolyEthylene Miscellaneous » Plastics
PEX	Cross-linked PolyEthylene Academic & Science » Chemistry
PEX	Pinoy Exchange Internet » Chat
PEX	Photo EXplorer Computing » Software
PEX	Pesticide Exposure Governmental » US Government
PEX	Pesticide Exposure Medical » Physiology
PEX	PetroCorp, Incorporated Business » AMEX Symbols
PEX	Pechora, Russia Regional » Airport Codes
PEX	Phigs Extensions To X Computing » Software
PEX	Personalized EXercise, Inc. Business » Firms
PEX	Proboard EXecutable program file (Proboard) Computing » File Extensions
PEX	Peel Exploration Ltd Business » ASX Symbols