Honestly, I think it's backwards. Either they _do_ matter because of some external factor (you mention network interoperability, though I'd like you to clarify... what exactly did you send over the network?), or they don't matter (if done right, you shouldn't even _notice_ that they start at 1 --- unless you test their truth value, which was the reason for the original departure from the usual practice in the first place).

You mention indexing... I _hope_ you're not using IntEnums for indexing tuples (or lists). :-o In such a scenario, you're really much better off cutting the middleman and using objects with attributes directly (an interesting insight: due to the way most objects in Python are implemented, you _still_ have the middlemen integers in the process -- only they are called "hash values" and they _truly_ don't matter:).