Multiple indices for TTree?

Hi,

TTree knows combined indices based on a majorname and a minorname. However, this gives one index in the end.

Is it possible to set up several indices, so that one can select events quickly depending on different quantities?

This would be useful when one wants to decide at runtime whether events shall be selected based on run and event number, or on other criteria (like time or something else).

Also, somewhat related: Do indices have to be unique, and if so, what happens if they are not?

Thanks,
Peter