i just explained the regex thing, if some of u wants the entire explanations, tell me, less Jethro_

on $*:text:/^!(start|stop)\sauto message$/iS:#:{
;; the $ on the begin will evaluate the reference, and it means that its a regular expression to be evaluated
;; we start using / then the ^ (anchor) means that,this reference needs to be on the beginning of the command
;; (start|stop) is the referenced text, the on text event, using regular expression, will analize if start or stop is on text after the ! 
;; \s means ''space'' it needs to have a space after the command !start or !stop
;; the $ (dollar sign) here, on the end, means that, this text/reference needs to be the last thing on line
;; so /^!(start|stop) auto message$/ needs to be the only thing on line, starting with !(start|stop) and end with message
;; closing the regular expression references using /
;; ''i'' after the close, means ''ignore all capital letters/uppercase''
;; ''S'' means, ignore all control codes, like colors, bold, underlined, reverse etc

  $iif($regml(1) == start, set $+(%,awflag,#) 1, unset $+(%,awflag,#))
;; if the on text found any match on the references, now $regml(0) its 1, so $regml(1) has a value, its ''start'' or ''stop''
;; the $iif condition will analize if $regml(1) == start, if yes, command 1, else command 2, in this case, else will be the reference ''stop''
;; $regml([name], N)
;; This can be used to reference the back referenced (items enclosed in parentheses) values returned by a call to $regex() or $regsub().
;; $regml explanation retired from the help file from mIRC who explains better

  describe $chan Auto join / leave massage $iif($regml(1) == start, started., stopped)
}

on !*:join:#:{
  if ($($+(%,awflag,#),2) == 1) { .timercheckops 1 1 checkops $nick $chan }
}
alias checkops {
  if ($1 isop $2) { describe $2 -> [MOD] $1 has joined. }
  else { describe $2 -> $1 has joined. }
}

on !*:part:#:{
  if ($($+(%,awflag,#),2) == 1) {
    if $nick isop $chan { describe $chan -> [MOD] $nick has left. }
    else { describe $chan -> $nick has left. }
  }
}