Po-Ching,
Unfortunately that forum is referencing old information from a previous
generation of our site . But I was able to dig this up using the Way Back
Machine:
https://web.archive.org/web/20071029084731/http://www.bro-ids.org/bro-works
hop-2007/slides/Bro-IPS.pdf
Does this help answer your question?
Thanks,
Jeannette