The tunes that have been contributed here have come from a variety of different sources. Many of them were typed up directly here in the website, while the bulk were uploaded (or mirrored) from pre-existing files, and all of this was originally done by a wide variety of people. This tends to result in a messy situation, where different people have had different understandings of the meanings of the ABC fields, and also provided (roughly) the same information in a variety of different ways and spellings :- under 'O:' (Origin), for instance, most people give a country, some have chosen to specify a village and/or a county. Likewise, some people's tunes come from 'England' while others are 'English'. This is understandable, and will probably always happen, but it messes the dropdown lists up something rotten, makes life more confusing for all the other users and makes more work for me thinking of ways to mitigate the situation - which I can do, but it'd be nice if I didn't have to spend my time doing it.
This is also the reason (along with simple comprehensibility) why the site uses its own names for the fields - to avoid the possibility of different understandings ( I've seen it "specified", for instance that ABC's "A:" field should mean the author of a song's lyrics. All the tunes I've ever seen use it as "Area", a more specific placing within "O:", the country ). If you use the editor panel, with its configurable field editors and dropdown lists, things will take care of themselves. But if you're working directly with ABC, as for instance uploading an ABC file, then I'd consider it a courtesy if you'd kind of check it over and think about how its values will go alongside what we have already. Thank you, and here's a list of the field names this website uses and their ABC equivalents to help you. Any field names not listed there will be translated into ABC by placing 2 '%' (percent) signs in front of them.
Also - as I said, I have some ad-hoc tweaks to take care of various sillinesses that I've noticed in the past, but sometimes things get past them, or maybe someone uploads a new file, with a new and ingenious perversity that I hadn't met before ... so the dropdown lists are always liable to get clogged up again with more peculiar values. If anyone notices this happening, please point it out to me and I'll lash up something to make it behave itself.