diff --git a/share/man/man5/style.mdoc.5 b/share/man/man5/style.mdoc.5
--- a/share/man/man5/style.mdoc.5
+++ b/share/man/man5/style.mdoc.5
@@ -304,6 +304,44 @@
 .Va critical_filesystems_ Ns Ar type
 .Ed
 .El
+.Ss Cross-References
+.Bl -dash -width ""
+.It
+For general information on references between man pages consult the
+.Xr mdoc 7
+page;
+specifically, the paragraphs describing
+.Sq \&.Xr
+and
+.Sx SEE ALSO .
+.It
+It is sometimes necessary to reference programs, libraries, or other
+documentation from outside of the
+.Fx
+base system; that is, man pages provided by
+.Xr ports 7 .
+Such cross-references should be formatted as:
+.Bd -literal -offset indent
+\&.Xr pkg 8 Pq Pa ports/ports-mgmt/pkg
+.Ed
+.Pp
+which renders as:
+.Bd -filled -offset indent
+.Xr pkg 8 Pq Pa ports/port-mgmt/pkg
+.Ed
+.Pp
+This way, the user is provided a link to relevant and potentially useful
+information, but they will not be confused when
+.Xr man 1
+informs them that the page cannot be found.
+In fact, they will know exactly where to obtain it.
+.Pp
+If a page is referenced several times in this manner, it is acceptable to
+omit the port's path for subsequent instances.
+The complete reference must be provided with the first occurance and in the
+.Sx SEE ALSO
+section.
+.El
 .Sh SEE ALSO
 .Xr man 1 ,
 .Xr mandoc 1 ,