ISRC, the International Standard Recording Code, is the internationally recognized identification code for sound and music video recordings.
An ISRC identifies a particular recording, not the work (composition and lyrical content) itself. Therefore, different recordings, edits, and remixes of the same work should each have their own ISRC.
Works are identified by ISWC.
Recordings remastered without significant audio-quality changes should retain their existing ISRC, but the threshold is left to the discretion of the record company.