AFAIK, this:

  $DataRead{'StringRead'} = substr($DataRead{'StringRead'}, -3);
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will set $DataRead{'StringRead'} to the last 3 characters of itself (or all if < 3 characters)... This:

  substr($DataRead{'StringRead'}, -3) = '' ;
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would remove the last three characters (or all if < 3 characters). Shirley ?

But in any case, would it not be easier to:

  if ($DataRead{'StringRead'} =~ s/(\t|\n|\r|\e\[Z|\eq)\z//) {
    my $term = $1 ;
    ....
  } ;
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