package MyPackage;

use constant {                         
     SCROLL_X = 1,
     SCROLL_Y=2,
     FLOW_X=3,
     FLOW_Y=4,
     ## and many more ... Let's say we have 20 constants

};
## this sub will tell us which constants are given, 
## and maybe in some other part of the package  other subs ## will know what to turn on and off};
sub which_constants {#??? }