[Groff] mdoc(7) interpretation differences (maybe groff bug)

[Steffen Nurpmeso]

Hello,

i finally come around to implement my proposed mdoc(7) reference
extension and yesterday i stumbled over a interpretation
difference (full source attached):

source:
  .It Fn at_quick_exit , Fn _atexit
  groff and mandoc agree.
  .It Fn at_quick_exit , _atexit
  Only mandoc gets that right.

mandoc:
     at_quick_exit(), _atexit()
                     groff and mandoc agree.

     at_quick_exit(), _atexit()
                     Only mandoc gets that right.

groff (1.22.3)
     at_quick_exit(), _atexit()
                groff and mandoc agree.

     at_quick_exit(), _atexit
                Only mandoc (and mdocmx) gets that right.

From my understanding of the manual the latter is a valid form to
mark "_atexit" as a .Fn, in which case the mdoc macros have a bug?

--steffen

mdoc-mid.1
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