  In a recent paper ([quant-ph/9610040]), Shor and Laflamme define two ``weight
enumerators'' for quantum error correcting codes, connected by a MacWilliams
transform, and use them to give a linear-programming bound for quantum codes.
We introduce two new enumerators which, while much less powerful at producing
bounds, are useful tools nonetheless. The new enumerators are connected by a
much simpler duality transform, clarifying the duality between Shor and
Laflamme's enumerators. We also use the new enumerators to give a simpler
condition for a quantum code to have specified minimum distance, and to extend
the enumerator theory to codes with block-size greater than 2.
