What does XPA stand for? Who knows anymore!
What does XPA stand for? Dunno! The XPA messaging system originally was built on top of the X Window System and XPA was the mnemonic for X Public Access, to emphasize that we were providing public access to previously private data and algorithms in Xt programs. Now that XPA no longer is tied to X, it can be argued that we ought to change the name (how about SPAM: simple public access mechanism ), but XPA is in wide-spread use in the astronomical community of its birth, and the name has taken on a life of its own. If anyone can think of what XPA now means, please let us know.
If you think this is bad, consider the MMT Telescope on Mount Hopkins, Arizona. When first installed twenty years ago, it featured an array of six 72-inch diameter mirrors. from which came its name: the Multiple Mirror Telescope. In spring of 1999, these mirrors were replaced by a single 21 and 1/2 -foot diameter primary mirror, the largest single-piece glass reflector on the North American continent. And now MMT stands for ... MMT!