The HTM command is used to view and set the high-transfer mode threshold. Additionally, it shows the incoming data rate, which is useful when monitoring how you are doing when relinking to the network.
- IRC Operators Guide (irchelp.org)
Less briefly, HTM is an IRC command for the operators to enable/disable and view info for high transfer mode, which is (as you might guess) for servers that are dealing with a lot of data. HTM changes the way the server works to more efficiently deal with a lot of data to/from other servers. (I don't know exactly how it does this, as I haven't done work with the ircd code.) Depending on the network, this could also be referred to as high traffic mode. Hybrid (EFnet's server) calls it transfer; Bahamut (for DALnet) says traffic.
On my computer, Bahamut says:
HTM is OFF(0), NOISY. Max rate = 40k/s. Current = 0k/s
Off is good in my case, and I shouldn't see any data flow, because no one connects to my server.
The help command (/raw or /quote help, that is) says the following. This is probably a much clearer explanation of what HTM does.
HTM [option]
When no [option] is given, HTM shows the current
High Traffic Mode rate and whether HTM is on or off.
[option] can be one of the following:
ON - Forces High Traffic Mode to be on. With
this on, ircd is more efficient in
reading server-to-server traffic and
oper traffic, but will be less efficient
than normal with normal client traffic.
OFF - Forces High Traffic Mode to be off.
(see above)
TO <rate> - Sets the High Traffic Mode rate to
<rate>. Ircd will automatically go
into High Traffic Mode when <rate>
is reached, and will automatically turn
it off when things calm down.
QUIET - When set, ircd will not notify opers
when it goes into and out of High
Traffic Mode.
NOISY - When set, ircd will notify opers
when it goes into and out of High
Traffic Mode.