I have an application that is perfectly happy reading so-called id3v2.4 frames if found in id3v2.3 tags. I'd like to request an option to ignore the strict enforcement of specific frames when written to id3v2.3 tags. If I want to write TSOA (Mp3tag's "ALBUMSORTORDER") and TSOP (Mp3tag's "PERFORMERSORTORDER") frames to an id3v2.3 tag then please enable a mechanism to let me do this. This is not the "corruption" of tags. I suppose there may be stupid applications or devices that will crash if they see an unrecognized frame (that really would be extraordinarily stupid) so by making this an option, you can leave it to the user.
This again gets back to the need for better user control over exactly which tags are written to a file. I'd still like to see a user-definable tag mapping system instead of having to break out the hex editor to figure out what Mp3tag did to a file.
Also, I notice that Mp3tag won't allow me to write a TCMP (MP3tag's "ITUNESCOMPILATION") frame with a value of 0 to id3v2 tags. This again is imposing some understanding of how Apple iTunes treats this tag, whereas my application doesn't treat it the same.
You have to understand that due to the completely screwed up id3v2 "spec" applications are having to extend this spec, plus they often have to deal with frames created by other applications. So tags like TCMP are no longer just used by iTunes and can be used and useful in other apps. Tagging standards, even for something like the years-old id3v2.3, are continuously evolving and I'm afraid Mp3tag doesn't quite have the necessary flexibilty to deal with this evolution.