format. If a command cannot work as requested using the requested
flow format, \fBovs\-ofctl\fR will report a fatal error.
.
+.
+.IP "\fB\-P \fIformat\fR"
+.IQ "\fB\-\-packet\-in\-format=\fIformat\fR"
+\fBovs\-ofctl\fR supports the following packet_in formats, in order of
+increasing capability:
+.RS
+.IP "\fBopenflow10\fR"
+This is the standard OpenFlow 1.0 packet in format. It should be supported by
+all OpenFlow switches.
+.
+.IP "\fBnxm\fR (Nicira Extended Match)"
+This packet_in format includes flow metadata encoded using the NXM format.
+.
+.RE
+.IP
+Usually, \fBovs\-ofctl\fR prefers the \fBnxm\fR packet_in format, but will
+allow the switch to choose its default if \fBnxm\fR is unsupported. When
+\fIformat\fR is one of the formats listed in the above table, \fBovs\-ofctl\fR
+will insist on the selected format. If the switch does not support the
+requested format, \fBovs\-ofctl\fR will report a fatal error. This option only
+affects the \fBmonitor\fR and \fBsnoop\fR commands.
+.
.IP "\fB\-m\fR"
.IQ "\fB\-\-more\fR"
Increases the verbosity of OpenFlow messages printed and logged by