MONITOR <action> [nick[,nick]*]

Manages the online-notification list (similar to WATCH elsewhere). The
<action> must be a single character, one of:

  +   adds the given list of nicknames to the monitor list, returns
      each given nickname's status as RPL_MONONLINE or RPL_MONOFFLINE
      numerics

  -   removes the given list of nicknames from the monitor list, does
      not return anything
  
  C   clears the monitor list, does not return anything
  
  L   returns the current monitor list as RPL_MONLIST numerics,
      terminated with RPL_ENDOFMONLIST

  S   returns status of each monitored nickname, as RPL_MONONLINE or
      RPL_MONOFFLINE numerics

For example:

  MONITOR + jilles,kaniini,tomaw

RPL_MONONLINE numerics return a comma-separated list of nick!user@host
items. RPL_MONOFFLINE and RPL_MONLIST numerics return a comma-separated
list of nicknames.