ipfw directives and order of precidence...

Is there a general rule I can apply when examining/editing ipfw entries?

Also, does each new entry have to have a unique rule number?

And, I think I can write a script to block code red infected machines (though I'm not sure it would do more than slim down my web server error message log), so I wonder what the top end for unique error numbers is, if required...

Inquisitively yours,
Network Security Dummy :o