+Invalid paths are ignored.
+Overridden by
+.Fl M ,
+ignored if
+.Fl l
+is specified.
+.Pp
+If
+.Ev MANPATH
+begins with a colon, it is appended to the default list;
+if it ends with a colon, it is prepended to the default list;
+or if it contains two adjacent colons,
+the standard search path is inserted between the colons.
+If none of these conditions are met, it overrides the
+standard search path.