ISRC codes are used to identify different recordings from one another either on a CD, vinyl record or upload to a digital service, and each starts off with a country code. The early ones that used code "US" ran out of numbers long ago, so "QM" was instituted as a replacement for all new codes in the US.
Now that's run out of numbers as well, so the Agency has now introduced "QZ" as the latest country code for the United States.
That being said, the Agency points out in a bulletin that the new country code should be used carefully and the following should be kept in mind:
- ISRCs that have already been assigned to recordings must not be changed
- Existing registrants should continue to use the "US" or "QM" codes that have already been allocated to them
- New users who are notified that their registrant code is to be used with the ‘QZ’ country code should never to use it with ‘US’ or ‘QM’ since that would result in ISRCs being generated that are a duplicate of previously assigned codes.
So basically, don't use the new code unless you've been told to do so.