+The optional \fIwildcard_mask\fR is an OpenFlow wildcard bitmask in
+hexadecimal that specifies the fields to wildcard. If no
+\fIwildcard_mask\fR is specified, the default value 0x2820F0 is used
+which specifies L2-only switching and wildcards L3 and L4 fields.
+Another interesting value is 0x2000EC, which specifies L3-only
+switching and wildcards L2 and L4 fields.
+.IP