[office-formula] Namespace / Named Expression ambiguity

I found something related to Namespaces and Names that seems to be ambiguous.  Given that a formula namespace the Named Expression identifier ($$) are both optional, how do we disambiguate a string like "OF:[.A5]"?  In this case "OF" could be a named range/expression or a formula namespace.

This is especially difficult for formulas being used for Style:Condition because they lack an equals sign.

-Eric