Okay... it's an acronym for, um, a musical group-- classic music, that is-- large group, like the ones you'd see in concert halls... the one in the capital city of Canada (oh, it's a palindrome by the way) and... well, the middle letter describes what type of orch... er, I mean Instrumental Ensemble that it is... It (the middle letter) is like a piece of classical music... an extended composition.... (writing clues is harder than it looks)