The
^ is used along with
haltdef, in order to stop and original message from showing.
halt will stop the rest of the event from happening, but it won't stop the default message. I don't know if it's a typo or not, but
>= should be
==. One more thing... if you also want to ignore the person in channel, you need to add a "-c" to the switches.
Hope this helps

Zyzzyx.