asterisk users - Sep 2005 - permit syntax question

Hi,

I'm newbie, please forgive me if this question was asked...

The demo conf has "permit=0.0.0.0/0.0.0.0", is the second 
0.0.0.0 is a network mask?  That is, if I need to permit
a /24 prefix, I should do "permit=192.168.1.0/255.255.255.0"?

Can I do "permit=192.168.1.0/24" instead?

If I have multiple prefixes, what is the proper way to list
them?  Should I do "permit=192.168.1.0/24,192.168.100.0/24" ?

Thanks a lot,

Min