* What led up to the situation?

     Checking for defects with a new version

test-[g|n]roff -mandoc -t -K utf8 -rF0 -rHY=0 -rCHECKSTYLE=10 -ww -z < "man page"

  [Use "groff -e ' $' <file>" to find trailing spaces.]

  ["test-groff" is a script in the repository for "groff"; is not shipped]
(local copy and "troff" slightly changed by me).

  [The fate of "test-nroff" was decided in groff bug #55941.]

   * What was the outcome of this action?


an.tmac:<stdin>:5: style: .TH missing third argument; consider document modification date in ISO 8601 format (YYYY-MM-DD)
an.tmac:<stdin>:36: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.
an.tmac:<stdin>:39: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.
an.tmac:<stdin>:42: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.
an.tmac:<stdin>:45: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.

Output from "test-nroff  -mandoc -t -K utf8 -rF0 -rHY=0 -rCHECKSTYLE=10 -ww -z ":

an.tmac:<stdin>:5: style: .TH missing third argument; consider document modification date in ISO 8601 format (YYYY-MM-DD)
an.tmac:<stdin>:36: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.
an.tmac:<stdin>:39: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.
an.tmac:<stdin>:42: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.
an.tmac:<stdin>:45: misuse, warning: .BR is for at least 2 arguments, got 1
	Use macro '.B' for one argument or split argument.


   * What outcome did you expect instead?

     No output (no warnings).

-.-

  General remarks and further material, if a diff-file exist, are in the
attachments.