MP3 Diags
Here you can see more details about the tags in the current file. Some of the fields / frames / items are shown in the tag editor, but for the others this is the only place where you can see them. The fields / frames / items that are used by the tag editor are shown in the upper part (as "Track#", "Artist", "Title", ...) while the rest are listed in the lower part. (In this example, the TLEN frame in the ID3V2.3.0 tag and various normalization-related items in the APE tag are ignored by the tag editor, and therefore they are shown in the lower part.)