Sort Fields Followup
Thanks to all the people who dropped by after the link from John Gruber, and indeed to him for (evidently) leading people here. Hopefully it's been useful. I appreciate all the comments, on vox and off. I hadn't really thought about the implications of posting an article like that on a site that requires the creation of a login, and of course these days it's not exactly a great idea to leave your email address lying around, so bonus points to those of you who managed to evade my (rather bad) spam filtering.
Some specific comments, then. Thanks to Rod Begbie for his comments about MusicBrainz, which has apparently supported sort data for a while, and Todd Larason for his dissection of ID3 tags that iTunes uses. I also updated the article to clarify how to apply fields to multiple items after an email from Chris Brummel made me realise that they weren't quite clear enough.
Speaking of applying fields to multiple tracks, Jacob Rus sent through an AppleScript that allows you to select a batch of tracks and apply a "Sort Artist" to each of them. It's worth reading the commentary at the beginning, as it's a little fragile (as scripts that rely on orders often are), but it also looks to be a useful fix for some of the UI issues noted in my original piece.