@yorickausyps Or are you suggesting that Mp3tag should not write TDRL in ID3v2.3 because it is not defined in the official standard?
BTW: The official standard for ID3v2.4 describes timestamps as:
Perhaps I'm mistaken, but I understood that all these time-variants are valid:
yyyy
yyyy-MM
yyyy-MM-dd
yyyy-MM-ddTHH
yyyy-MM-ddTHH:mm
yyyy-MM-ddTHH:mm:ss
or with examples:
1987
1987-12
1987-12-31
1987-12-31T23
1987-12-31T23:59
1987-12-31T23:59:59