Comment #4 on issue 2861 by [email protected]: Patch: Adds tick mark to scripts
http://code.google.com/p/lilypond/issues/detail?id=2861
Well, the image I've put in comment 2 is from music typesetting, so it clearly exists. It's also a _very_ common way to indicate breathing in hand annotations to vocal music.
Wikipedia says "check mark" is US for tick - we certainly say tick or tick mark in the UK. We also say that marking something as correct is "giving it a tick".
As I'm British, I called it a tick mark, which is what it is.
