Example: renaming files with an action (...group, actually).
Without variables: 453 characters
$iflonger($num(%track%,2)$validate([. $replace($meta_sep(artist, & ), / , & ) - [%title%]],),0,$left($num(%track%,2)$validate([. $replace($meta_sep(artist, & ), / , & ) - [%title%]],),$sub(248,$len($replace(%_folderpath%,\Pop,\Pop lossless,\Class,\Class lossless)))),%_filename%)$iflonger($replace(%_folderpath%,\Pop,\Pop lossless,\Class,\Class lossless)$num(%track%,2)$validate([. $replace($meta_sep(artist, & ), / , & ) - [%title%]],),249,…,)
With variables: 273 characters (-40%)
$puts(T,$num(%track%,2)$validate([. $replace($meta_sep(artist, & ), / , & ) - [%title%]],))$puts(F,$replace(%_folderpath%,\Pop,\Pop lossless,\Class,\Class lossless))$iflonger($get(T),0,$left($get(T),$sub(248,$len($get(F)))),%_filename%)$iflonger($get(F)$get(T),249,…,)