use constant ROTATE => 1; 
use constant HOLD => 2; 
use constant FLASH => 3; 
use constant NUM_MODES => 3;
# etc.

my %modestring = (
  +ROTATE => "a",
  +HOLD => "b",
  +FLASH => "c",
  # etc...
);

##</code><code>##

sub ROTATE () { 1 }
# etc.

my %modestring = (
  +ROTATE => a,
  # etc.
);

##</code><code>##

.