The Classification Tree Method is a well established principle of chossing values to use when testing software algorithyms. For a given set of input parameters to a software function, there could be an infinite number of combination and values to choose from to ensure the software under test works. To help choose values a block of theory exists based upon the classification tree method.
For those of you interested in this topic I have posted a video clip on YouTube.
http://www.youtube.com/watch?v=P0JLfaKvmjE
The clip describes the principles behind the classification tree method as a way of generating test cases for software.
This clip is the first part in a two clip presentation, focussing on the theory behind the method.
I have a power point presentation on this which I can email to people who are interested in it further.