-This command is primarily useful for debugging Open vSwitch. As
-discussed in \fBdump\-flows\fR, these entries are
-not OpenFlow flow entries. By deleting them, the process that set them
-up may be confused about their disappearance.
+The \fBadd\-flow\fR command succeeds only if \fIflow\fR does not
+already exist in \fIdp\fR. Contrariwise, \fBmod\-flow\fR without
+\fB\-\-may\-create\fR only modifies the actions for an existing flow.
+With \fB\-\-may\-create\fR, \fBmod\-flow\fR will add a new flow or
+modify an existing one.
+.IP
+If \fB\-s\fR or \fB\-\-statistics\fR is specified, then
+\fBmod\-flows\fR prints the modified flow's statistics. A flow's
+statistics are the number of packets and bytes that have passed
+through the flow, the elapsed time since the flow last processed a
+packet (if ever), and (for TCP flows) the union of the TCP flags
+processed through the flow.
+.IP
+With \fB\-\-clear\fR, \fBmod\-flows\fR zeros out the flow's
+statistics. The statistics printed if \fB\-s\fR or
+\fB\-\-statistics\fR is also specified are those from just before
+clearing the statistics.
+.
+.IP "[\fB\-s\fR | \fB\-\-statistics\fR] \fBdel\-flow\fR [\fIdp\fR] \fIflow\fR"
+Deletes the flow from \fIdp\fR's flow table that matches \fIflow\fR.
+If \fB\-s\fR or \fB\-\-statistics\fR is specified, then
+\fBmod\-flows\fR prints the deleted flow's statistics.
+.
+.IP "\fBdel\-flows\fR [\fIdp\fR]"
+Deletes all flow entries from datapath \fIdp\fR's flow table.