+utility is compliant with the
+.St -p1003.1-2008
+specification of
+.Xr man 1
+.Fl k .
+.Pp
+All options, the
+.Nm whatis
+command, support for logical operators, macro keys,
+substring matching, sorting of results, the environment variables
+.Ev MANPAGER
+and
+.Ev MANPATH ,
+the database format, and the configuration file
+are extensions to that specification.
+.Sh HISTORY
+Part of the functionality of
+.Nm whatis
+was already provided by the former
+.Nm manwhere
+utility in
+.Bx 1 .
+The
+.Nm
+and
+.Nm whatis
+utilities first appeared in
+.Bx 2 .
+They were rewritten from scratch for
+.Ox 5.6 .
+.Pp
+The
+.Fl M
+option and the
+.Ev MANPATH
+variable first appeared in
+.Bx 4.3 ;
+.Fl m
+in
+.Bx 4.3 Reno ;
+.Fl C
+in
+.Bx 4.4 Lite1 ;
+and
+.Fl S
+and
+.Fl s
+in
+.Ox 4.5
+for
+.Nm
+and in
+.Ox 5.6
+for
+.Nm whatis .
+The options
+.Fl acfhIKklOTWw
+appeared in
+.Ox 5.7 .
+.Sh AUTHORS
+.An -nosplit
+.An Bill Joy
+wrote
+.Nm manwhere
+in 1977 and the original
+.Bx
+.Nm
+and
+.Nm whatis
+in February 1979.
+The current version was written by
+.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv
+and
+.An Ingo Schwarze Aq Mt schwarze@openbsd.org .