Re: [office-formula] Valid sheet name characters

Rob Weir:
> In OOXML sheet names can contain any characters, even control characters if they are hex-encoded.

Okay, clearly we need to allow arbitrary characters as well.
I'm fine with tweaking text to say that documents SHOULD limit
themselves to a subset, while continuing to be ABLE to represent more.

This is a potential issue with using xml:id to identify
named expressions; since xml:id values must be unique, and
named expressions can be local to a sheet, any xml:id value for
a named expression's name may need to include a sheet name.
xml:id doesn't allow arbitrary characters, so we would have to
define an encoding or continue to not use xml:id for this purpose.

--- David A. Wheeler