Suse 9, [kacpid] and display of "ps"

[kitepilot at kitepilot.com]

WHAT DO THE BRACKETS mean? (down below) 

Hello there: 

I have a Suse 9 machine as:
 ------------------------------------------------------------------
# uname -r
2.6.5-7.97-smp
# cat /etc/issue 

Welcome to SUSE LINUX Enterprise Server 9 (i586) - Kernel \r (\l).
 ------------------------------------------------------------------ 

I am trying to determine if the acpi daemon is running, but all I find is: 

# ps aux|grep acp
root         5  0.0  0.0     0    0 ?        S<   Sep22   0:00 [kacpid] 

There is no reference whatsoever to "kacpid" in /etc/init.d 

Also, WHAT DO THE BRACKETS in [kacpid] mean?
I have always wondered about those brackets and "man ps" doesn't really 
help... 

Appreciate any help.
Thanks
Enrique