See also ...
iTunes metadata
$ifgreater(%ITUNESADVISORY%,3,'Explicit',$ifgreater(%ITUNESADVISORY%,1,'Clean','None')
$replace(%ITUNESADVISORY%,0,'None',2,'Clean',4,'Explicit')
New with Mp3tag v2.59
$ifgreater(%ITUNESADVISORY%,1,'Clean',$ifgreater(%ITUNESADVISORY%,0,'Explicit','None')
$replace(%ITUNESADVISORY%,0,'None',1,'Explicit',2,'Clean')
See also ...
https://docs.mp3tag.de/mapping/#tag-fields-exclusive-to-mp4
DD.20140419.1918.CEST, DD.20140420.2037.CEST