extended bitvectors on spells

I was wondering if someone could tell me how to add an new affected_by spell to the extended bitvectors. I have tried to add the spell to the section in mud.h and recompile and It does not show the bits when I create the spell in the game. Is there a special section to define the bitvector so that the game can reconnize it? I seen how regular bitvectiors are listed but haven't seen the layout for ex_bv.

thanks for your help in advance.