Security Configuration Settings?

Im in the process of trying to secure a SunOS name 5.8 Generic_108528-29 sun4u 
sparc SUNW,Sun-Fire-280R, using settings per 
http://sabernet.home.comcast.net/papers/Solaris.html.  I have a few questions 
about the settings and due to the fact that this box is supposed to look as 
much like a production box but I have no budget for things like 'stronghold' 
etc.  I must use as much free ware as possible.

On the above mentioned page under "Access Controls" section 4 'Only add 
accounts for users who require access to the system. If using NIS, use the 
compat mode by editing the /etc/nsswitch.conf file:

passwd: compat'

I don't understand and haven't been able to find anything related to what 
describes 'compat'.  Can any one provide me with why it is a good measure to 
change this from 'files' to 'compat' and what other changes may be necessary or 
what exactly is the difference?

Thanks

I can only hope the moderators of this group find this worthy of being posted.