ID3 tags DISCNUMBER and TOTALDISCS should be supported
This is especially important for audio books. Because there are multiple "Track nr. 1" (one on each disc), the mp3-players first look up the disc number, then the track number. Up to now I set the disc number with another software. It would be nice if I could do this (as well as the number of discs) with eyeD3, too.