Here is a working example:
http://test-e3.scene7.com/is/content/AndrejSokoll/pool/xml/rulesetPool_120803.xml
or the same XML under /asset/ context:
http://test-e3.scene7.com/asset/AndrejSokoll/rulesetPool_120803.xml
As with all ruleset development, test on a staging environment before live deployment.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ruleset SYSTEM "RuleSet.dtd">
<ruleset><asset-rule ForwardTo="content"><expression>^(.+).pdf</expression><substitution>$1pdf</substitution></asset-rule>
<asset-rule ForwardTo="agm"><expression>^dynamic/(.+).pdf$</expression></asset-rule>
<asset-rule ForwardTo="content"><expression>^(.+).swf$</expression><substitution>$1</substitution>
</asset-rule><asset-rule ForwardTo="flash"><expression>^dynamic/(.+).swf$</expression><substitution>$1</substitution></asset-rule>
<asset-rule ForwardTo="content"><expression>^(.+).xml</expression><substitution>$1</substitution>
</asset-rule><asset-rule ForwardTo="image"><expression>^pool/(.+).gif$</expression></asset-rule>
<asset-rule ForwardTo="content"><expression>^(.+).gif$</expression><substitution>$1</substitution>
</asset-rule><asset-rule ForwardTo="image"><expression>^(.+).jpg$</expression></asset-rule>
<asset-rule ForwardTo="image"><expression>^(.+).png$</expression></asset-rule>
</ruleset>