/help /haltdef

^ is used when you want to use halt/haltdef.

Example:

This will make all text appear twice (once in the original form, once colored greed).
Code:
on *:text:*:*: {
  echo -a 03 $+ $strip($1-)
}


If you wanted only your green version to be displayed:
Code:
on ^*:text:*:*: {
  haltdef
  echo -a 03 $+ $strip($1-)
}


To see some other prefixes:
/help prefixes