ircII help: on list

Usage: ON [#|+|-|^|&|@]LIST [-|^]<parameters> [action]
  When LIST is activated any outputline will be modified
  by [action].
  For example:
    ON LIST "* 5 *" /ECHO NUMBER OF USERS: 5
  
  The parameters are as follows:
    $0    channel name
    $1    number of users on channel
    $2-   topic of channel