I use several tools to manage my music collection:
Mediamonkey for most tagging
Foobar for replaygain
mp3tag for inserting album art and converting replaygain to Itunes soundcheck.
Unfortunately the tag writing in these apps was not equal, so I just wrote a lot of tags in foobar (date values that were written wrongly in mediamonkey) but ended up with 2.4 tags that mediamonkey can no longer read. I have changed default value for foobar to 2.3 now, but my collection is still messed up. Can I change my tags from 2.4 to 2.3 using mp3tag?