Write to the COMPILATION tag (What mapping should I use)

I would like to write the COMPILATION tag in mp3tag.

The trouble is if I save the file and open the properties in foobar2000 the tag appears as ITUNESCOMPILATION.

I'm not sure what mapping I need in order for this to work in mp3tag.

I don't think that you need any mapping at all. foobar2000 decides to display the compilation field as ITUNESCOMPILATION, but if you write from Mp3tag COMPILATION is the way to go (it writes to TCMP for ID3v2 and cpil for MP4).

The trouble is I'm writing to FLAC and MP3.

If I write to the COMPILATION tag for FLAC, it's fine but then in foobar2000 it's different to the ITUNESCOMPILATION for the MP3s.

I suppose all I can do is map VorbisComment like so?