What are those numbers like 1M1, 1M2 in some articles and liner notes?
Those are production “slate” numbers. 1M1 is the first piece of music heard in reel one of the movie, for example (usually a reel is 10 min long, so a two-hour movie has 12 reels), 1M2 is the 2nd piece in reel one, etc. (The character name “R2D2” from Star Wars, by the way, was famously inspired by George Lucas liking the sound of it when someone called for “reel 2, dialogue 2” during the making of an earlier film.) We include these from time to time for historical purposes and also to help people understand what they are listening to when the music is presented out of sequence on the CD.
