One of the things that's confused me the most in the process of ripping my CDs to FLAC, converting said files to AAC for my iPod, and reading said files using Mp3tag, is how each software program/codec seems to handle "Artist Sort" differently. I rip my CDs to FLAC for playback through my Squeezebox Touch, which runs Logitech Media Server, which can only read "ARTISTSORT" apparently. Typing this in to dBpoweramp CD Ripper as a new tag worked fine. This morning, I thought I'd experiment by creating what I thought would be the same tag in "ArtistSort," but for some reason when I typed this in as a new tag in CD Ripper it wasn't even created in the resulting FLAC files! On top of all this, whenever I convert my FLAC files to AAC for transfer to my iPod I have to create a Mapping rule in dBpa Music Converter that changes "ARTISTSORT" to "Artist Sort" (i.e., add a space), which appears to work in iTunes, at least. To add further confusion, however, regardless of whether it's a FLAC or AAC file, Mp3tag always reads it as "ARTISTSORT" in all caps!

Does anyone have any insight into why this tag is so sensitive to permutations in capital letters, spaces, etc.? I know that each container/file format has its own peculiarities regarding how it handles certain tags, but this one has created the most headaches for me. Specific to dBpa, in order for CD Ripper to write the tag correctly when ripping CDs to FLAC, do I really have to enter it as all caps (ARTISTSORT) as opposed to a combination (ArtistSort)? I was the under the impression that capital vs. lower case didn't matter in terms of how VorbisComments works, but is there something in the dBpa software that's sensitive to this?