Guidelines for wearing your chapter name's letters

[Bee]

I'm looking for guidelines on use of chapter letters.

Like, if I'm a member of the Delta Zeta chapter of XYZ Sorority, are the chapter reference guidelines solely with the Sorority? Or is it totally acceptable to go around wearing the DZ letters?

I mean, NO! That can't possibly be OK. But I am searching for some official guideline somewhere. Where common sense does not, unfortunately, prevail.

This is happening and I'm trying to point out an error in judgment respectfully. Or, if I'm wrong here, I need to see it in writing somewhere.

Help?