Question about rule numbers and Syslog

["Truax, Shawn (MBS)" <Shawn.Truax () mbs gov on ca>]

When you receive a syslog message from Snort it gives a rule number of
#:###:#. For example 1:255:8 is DNS Zone Transfer TCP.  I know that the
middle number is the sid for the rule.  My question is what are the other 2
numbers, where do they come from and are they in the acid database anywhere.

Shawn Truax
Sr. Security Specialist
Corporate Security
155 University Ave.
Toronto, Ontario
M5H 3B7
(416)327-1107