Undernet server features.
-------------------------

This document is supposed to list the features that undernet supports and
provides to clients, and which version of ircu this was added.  Additional
numeric replies should be added here too.

Extended Who information: (WHOX)
 Version: unknown, but at least 2.10.07+

 This is described in the file 'readme.who'

USERIP:
 Version: unknown, but at least 2.10.07+

 This works the same as userhost, but returns the IP instead, useful for
 setting a ban on someones IP address instead of their nick.
 usage:
  USERIP nick[,nick...]
 returns:
  RPL_USERIP (307)
  :server.name 307 target nick[*]=[+|-]user@host...

RPL_ISUPPORT:
 version: 2.10.08+
  
 This sends a numeric during client signon that lists various features that
 ircu supports.  This allows client and script writers to know what features
 they can use, and various parameters about the irc server.  The numeric
 used is '005' to try and maintain some semblance of compatibility with
 dalnet which has a similar feature.  The 005 numeric may be split across
 multiple lines if the length exceeds 512 characters.

 The format is:
  :servername 005 target feature1 feature2... :are supported by this server.
  :servername 005 target feature200... :are supported by this server.

 features are either a word describing the feature eg: 'SILENCE', or a word
 describing the feature and an equals and a list of parameters.  
 eg: SILENCE=15 (says that we support silence, and we support up to 15 of
 them per user), or FOO=12,3 (says we support FOO with parameters 12 and 3)
 for example 2.10.08 lists:

 :test.undernet.org 005 test SILENCE=15 WHOX WALLCHOPS USERIP CPRIVMSG 
   CNOTICE MODES=6 MAXCHANNELS=10 MAXBANS=30 NICKLEN=9 TOPICLEN=160
   KICKLEN=160
 
 NOTE: Versions prior to 2.10.08+ use numeric 005 as part of 'MAP', so
 005 should be /not/ be used after the server registration has occured.
 (ie: after END_OF_MOTD has arrived).

MAP:
 Version: unknown, but since 2.9.30 at least, updated in 2.10.08
 
 /map shows the servers as the server percieves them, who's connected
 to who in a pretty display.  In version 2.10.08 it also lists the
 amount time time it takes a message to get /from/ a server to the local
 server - this measures the one way lag only, in 2.10.08 it also lists
 the number of clients that are currently on that server.
 The lag estimation is very approximate and depends on people changing nick
 and joining channels, so the less clients on a server the less reliable the
 lag estimation is.

 Map prior to 2.10.08 uses:
  RPL_MAP     005
  RPL_MAPMORE 006
  RPL_MAPEND  007
 Map changed in 2.10.08 to allow for ISUPPORT on numeric 005, the new
  numerics are:
  RPL_MAP     015
  RPL_MAPMORE 016
  RPL_MAPEND  017
 
WALLCHOPS:
 Version: unknown, but since 2.10.07
 
 WALLCHOPS sends a message to all channel operators (@)'s on a channel.
 It does /not/ require you to be op'd (@'d) to do so.  This is a feature.
 
 syntax:
  WALLCHOPS #channel :message
 or:
  NOTICE @#channel :message

 this sends:
  :user NOTICE @#channel :message
 to clients that are @'d on the channel.

CPRIVMSG/CNOTICE:
 Version: unknown, but since 2.10.07

 CPRIVMSG/CNOTICE are a way around target limiting in recent undernet
 servers.  Undernet servers prevent you from sending messages to too many
 people at once in an attempt to help cut down the amount of spam that
 occurs on the network.  Because there are several situations where you want
 to send messages to lots of people that are on the same channel as you
 (autogreet's and gamebots for example) an 'escape' was made in the form
 of CPRIVMSG/CNOTICE.  These allow you to send a privmsg/notice to a person
 on a common channel if you are op'd (@'d) without incuring a target
 penalty.  If you see 'Target changed too fast' messages, you should
 probably be using these commands.

 Syntax:
  CPRIVMSG #channel nick :Message
  CNOTICE #channel nick :Message
 
 Results are the same as for 'PRIVMSG' and 'NOTICE' respectively.

SILENCE:
 Version: unknown, 2.9.32 at least.

 Silence is a server side ignore.  You can /silence +hostmask or
 /silence +nick, to add someone to your silence list, or use /silence
 -hostmask to remove it.  /silence will list your 'silence list'.
 you can /silence nick, to see someone elses silence list (useful for
 helping someone).  Silence is preferably used as a last resort as it
 tends to use server CPU time.  Undernet typically only allows 15 silences
 per user.  in 2.10.08+ this information is available in the RPL_ISUPPORT
 line.

 Syntax:
  SILENCE +hostmask
  SILENCE +nick
  SILENCE -hostmask
  SILENCE -nick
  SILENCE nick

 reply:
  RPL_SILELIST      217
  RPL_ENDOFSILELIST 218
 
User modes:
 Version: various

 Undernet supports these additional user modes:
  +d: Deaf & Dumb.  This user will not get any channel traffic.  Used for
      bots.
  +k: This user cannot be kicked, deop'd or /kill'd.  This usermode may only
      be set by a server, it may not be set by a user.  This is used by
      undernet service bots (X/W/UWorld etc)
  +g: List channel HACK:'s
  +s: Server messages - takes a parameter of which masks to send, see
      'snomask.html' for more details. (2.10.0+)

LIST:
 Version: Unknown

 List now takes various parameters to allow you to quickly and efficiently
 find interesting channels.  These are:

 >n or <n   show channels with less than or greater than 'n' users
            respectively
 C>n or C<n show channels that have existed for less than or greater than
            'n' minutes.
 T>n or C<n show channels that have had their topic changed in less than or 
            greater than 'n' minutes.

 Additional Numerics:
  RPL_LISTHELP 334

Additional Topic Numerics:
 Version: Since the dawn of time.

 Topic also lists who set it and when they set it.

 Additional Numerics:
  RPL_TOPICWHOTIME 333
 
 Straight after the topic:
  :server.name 333 #channel Isomer 923423442
 where the number is seconds past 00:00 1970-01-01 that the topic was set.


INVITE list:
 Version: 2.10.08+

 /invite without any parameters lists which channels you have an outstanding
 invite to (ie: an invite to a channel which you haven't joined)
 
 Additional Numerics:
  RPL_INVITELIST      336
  RPL_ENDOFINVITELIST 337

NICK change:
 Version: Since the dawn of time.

 Undernet prevents you from changing nick on a channel while your banned.
 Undernet prevents you changing nicks more than once per 30 seconds, you
 get one 'free' nick change if you haven't changed nick recently.

 Additional Numerics:
  RPL_BANNICKCHANGE 347
  RPL_NICKTOOFAST   349

Target limiting:
 Version: Recent 2.10.07ish at least.

 Undernet prevents you from changing 20 targets per 2 minutes.  A target
 is a 'Nick' or 'channel'.  This is to prevent spam.  If you message more
 than 20 people or join more than 20 channels in two minutes then you'll
 start getting 'Target change too fast' and will have to wait before you
 can start talking.  See CPRIVMSG/CNOTICE above for information on how to
 avoid this.

 Additional Numerics:
  ERR_TARGETTOOFAST 349


