I have been under the impression that the FLAC standard is using the "Publisher" tag for the record labels name, and the "Catalog #" for exactly what it says. Anyway that was the conclusion I came to when I researched (googled) this, and how I have been tagging my music
Well - those are cool choices if you always plan on only staying with those songs in that single file format (and never transcode to MP3 for example).
However - I just ran the following test and can now confirm why I specifcally use LABEL and LABELNO:
Since I use three different tools for metadata management (dbPowerAmp, Tag N Rename and MC) - it was important to try to get as much "agreement" on certain tag fields as possible. And leave MC out of it for the moment.
1. Ripped a single track from an Animal Logic CD in dbPoweramp into FLAC format - just so I could see it's default tag placement
2. Upon a quick inspection - I could see a tag called "Label" got a value of I.R.S. Records (just using the default metadata retrieved by dbPowerAmp)
3. I did not see any reference to LABELNO in this first pass
4. I then open the same FLAC track in Tag N Rename and saw that T&R picked up the LABEL value of I.R.S. Records (placed presumably by dbPowerAmp)
5. I then manually typed the Animal Logic CD number into the "Catalog #" field within Tag & Rename
6. I then reexamined the full tag structure in dbPowerAmp and now can see a new tag called LABELNO (obviously filled by T&R in step 5)
7. If I then open the track in MC (with my custom fields called LABEL and LABELNO on as standard) these fields are immediately filled with values places within Steps 1-6
8. Nowhere in any of these files edited by my specific tools is there any mention of tags named Publisher or Catalog #.
So - for my personal library management - using any other fields other than LABEL and LABELNO makes no sense - as it seems that at least the two other tools that I use regularly won't pick them up should I need to transfer a file over to dbPowerAmp or Tag N Rename.
The easiest solution was to add these two (LABEL and LABELNO) to my MC db and it takes care of tags in all three apps.
VP