EarlyRules

$EarlyRules is a configuration variable that allows you to add your own functionality without changing the core wiki.pl file. It contains perl commands acting on $text, before it's HTML, ( To change the HTML source of the formatted wiki page, use $LateRules.)

Is there a good example of the use of $EarlyRules?

Not yet. The main reason one would want to use $EarlyRules is to override the default wiki behavior. For example, if one wanted to override the rule that turns ---- into <hr> (horizontal line), one would have to do it in $EarlyRules. --CliffordAdams

See $LateRules for more information about how to use rules and an example.