How does Mp3Tag map ID3v2.3 frames?

Where can I find a complete list of how Mp3Tag maps the frames to the field names used on-screen?
i.e. in Mp3Tag there is a column field named 'Date', but it's impossible to tell exactly which frame this is
How Mp3Tag reads year from correctly formated TYER, TDRC or TDRL tags. If you have both TDRC and TDRL, which one is read by Mp3Tag?