While I never use these constants for anything other than setting variables I declare, it would be easy to use them otherwise. I started this habit when I was first learning perl as a way of distinguishing "logical" and "numerics" in my code and for setting "logical" options in some modules (like DBI).

For example:

$gDBHandle = DBI->connect
  (
    'dbi:Oracle:' . ORATNS, ORAUSER, ORAPASS,
    {
      AutoCommit  => FALSE,
      PrintError  => FALSE,
      RaiseError  => FALSE,
    }
  ) || die 'Could not connect to Oracle ['.$DBI::errstr.' - '.$DBI::er
+r.']';
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Thank you for the suggestion.