more ODP bits
ODP::Passport is a "centralised authentication system for editor produced tools", and is also pretty nifty. Go read more about it here: http://passport.rpfuller.org/.
This page you're looking at is where you can find some PHP that can be used to protect other PHP tools using ODP::Passport. It's a nice and simple way of dealing with authentication - after a couple of steps, you can just include it at the top of a script to add authentication.
Here's the bits: