The firewall executes the rules in ascending order, meaning that rule 100 is executed before the rule 200. The sequence of the rules is important as each IP request is checked against a matching rule. As soon as there's matching rule it is being executed. All other subsequent rules are being omitted.
For instance, suppose there're the following rules defined:
Order Source Destination Policy Log Level
100 net loc DROP info
200 loc all ACCEPT info
300 fw net ACCEPT info
400 fw loc ACCEPT info
500 all all REJECT info
Each IP request is tried to be matched with a rule. For instance an IP request from the internet (net) to the firewall (fw) is being rejected by rule 500.