Update the information, (and likely break all formatting rules).

svn path=/head/; revision=140898

share/man/man4/nmdm.4

@@ -32,23 +32,21 @@
 .Sh DESCRIPTION
 The
 .Nm
-driver provides support for a device-pair termed a
-.Em null modem pair .
-A null modem pair is a pair of character devices.
-Each device provides to a process an interface identical
-to that described in
-.Xr tty 4 .
-However, whereas most other devices which provide the
-interface described in
+driver provides two 
 .Xr tty 4
-have a hardware device of some sort behind them, the
+devices connected
+by a virtual "null modem" cable.
+.Pp
+If either of the two tty devices have the CDSR_OFLOW bit
+("stty dsrflow")
+set in their line discipline, the 
 .Nm
-device has, instead, another process manipulating
-it through the other half of the pair.
-That is, anything written on the first device is
-given to the second device as input and anything written
-on the second device is presented as input on the first
-device.
+device will emulate the speed configured in the
+.Xr termios 4
+settings.
+The speed emulation works independently in the two directions,
+controlled by the slower ends termios settings (c_ispeed, c_ospeed,
+CS5...CS8, CSTOPB and PARENB).
 .Sh FILES
 .Bl -tag -width /dev/nmdm[N][AB] -compact
 .It Pa /dev/nmdm Ns Ar N Ns Op Pa AB
@@ -59,9 +57,16 @@ node has a matching
 .Pa B
 node.
 .El
+.Pp
+The
+.Nm
+driver implements "on-demand device creation" so simply accessing a
+given instance in /dev will create it.
 .Sh DIAGNOSTICS
 None.
 .Sh SEE ALSO
+.Xr stty 1 ,
+.Xr termios 4 ,
 .Xr tty 4
 .Sh HISTORY
 The