The term RECORD NUMBER is a combination of two crossword solutions: SONG (4 letters) and RPM (3 letters). RECORD NUMBER is a term used to refer to the unique identifier assigned to a particular recording, such as a SONG or album. It is usually composed of a combination of letters and numbers, and is used to differentiate one recording from another. The acronym RPM stands for revolutions per minute, which is a measure of the speed at which a RECORD is played. This is important because the speed affects the sound quality of the recording.