I think you might be confusing transliteration with substitution
When you use the tr operator you only have 3 options ( copied from perldoc perlop)
c Complement the SEARCHLIST.
d Delete found but unreplaced characters.
s Squash duplicate replaced characters.

If you want to strip out tabs using tr you would do something like $actionData =~ tr/\t//d; The substitution equivalent would be  $actionData =~ s/\t//g