how rulesets work

[Erick Calder <e...@arix.com>]

I have a few questions:

1) can I use use an s/// instead of simple // in a rule-set?
2) if so, will it modify the contents of the {body|header|etc.}?
3) if 2) above is the case, will those changes remain local to the 
   excution of the particular .cf the rule is in? or will other 
   rule-sets see those changes?
4) if 3) above is the case, how can I make modifications to these
   contents without propagating them into other rule-sets?

thanks in advance,

ekkis