kate is an extraction of the paypal SDK vendor code, normally found in a file called: paypal_platform_ruby_sdk.zip
It has been reformatted, and slightly modified to be useful to me.
Why the name? She is married to Prince William. Why Prince William? He's your PrinciPal, which is like your Paypal.
(Okay, it's a stupid reason to use a nice four letter name, suggest something better)