$text cannot be used as a Start-up Action

FYI, $text (remaining unmatched text) cannot be used as
a start-up action to preprocess text before parsing:

  Global symbol "$text" requires explicit package name at ./pt2hum line 58.
  Execution of ./pt2hum aborted due to compilation errors.

my $g2 = <<EOG;

{ ##Alter separation character
  $text =~ tr/_/ /; }

foo: /\w+/

EOG

my $parser = Parse::RecDescent->new($g2)
  or die "bad grammar\n";

Colin