I don't want to be mean, but questions like this are really easy to figure out if you google or search the site. By all means ask if you can't figure something out, but if it took me a minute and a half to access this information, it probably wouldn't have taken you much longer to do it yourself. Anyway, hopefully those links are helpful for other acronym issues.
ETA: (which means edited to add) COBI beat me to it!
=) this one drove me nuts for the longest time too, Most of em I could figure out , But this one i actually had to stumble across someone writing it out in a post =)