Here is the complete syntax:
FILE/A,ALL/S,REQ/S,ALF=AppendLineFeed/S,LF=LFORMAT/K, T=Title/K,Ar=Artist/K,Al=Album/K,Y=Year/K,C=Comment/K,G=Genre/K,Track/K/N

Here is the help page you see, if you enter "?" after you started MP3IDs with a "?":

Help-Page:
FILE/A - is the mp3 filename.
ALL/S  - if you want all infos about a mp3 file.
REQ/S  - display the infos in a mui-requster.
ALF/S  - append a linefeed at the end.

LFORMAT=ftaAycCglbzdsqmkKvV
  With this argument you can specify the format for displaying mp3 tag infos:
    %f -> filename %t -> title    %a -> artist   %A -> album   %y -> year
    %c -> comment  %C -> comment2 %g -> genre    %l -> layer   %b -> bps
    %z -> filesize %d -> duration %s -> seconds  %q -> freq    %m -> mode
    %k -> track    %K -> track2   %v -> mpegaVer %V -> ID3Ver
    \n -> linefeed \t -> for a tab

  'filesize' is in bytes, 'duration' in mm:ss 'frequency' in Hz and the 'mode'
  can be stereo, j-stereo, dual-channel or single-channel.
  
  If you only specify a filename this 'lformat' is used
    lformat = "'%a - %t (%A)\n%d MPEG%v-%l %m %bkps %qHz\n"

T=Title/K,Ar=Artist/K,Al=Album/K,Y=Year/K,C=Comment/K,G=Genre/K,Track/K
  These args are for writing the appropriate id3tags to the file.