>> This usage is IMHO not documented in the troff manual § 7.4 or
>> groff manual § 5.25.
>
> It's documented in the groff manual in section 5.19; see the
> sentence "Strings, macros, and diversions (and boxes) share the same
> name space" and the following few paragraphs.
... and please look up what `.unformat' does – in the groff info
manual, an example is given in the documentation of the `.ds' request.
> You're right that, because this discussion involves multiple
> objects, it shouldn't be documented under just one of them without
> at least pointers to it in the documentation of the others.
Please open a bug tracker issue and ideally provide patches there...
Werner
