What is this population form script called?

[robhamblen]

I have been asked by the website owner of a website I built, if I could implement a form for reserving books, similar to one of these: http://www.highlanderbookstore.com/b...26FF7EDD8148D8 or http://www.bkstr.com/CategoryDisplay...04-1?demoKey=d but when I went looking into it, I really didn't know what it would be called. Looks like some sort of variation on a chain script but only populates the next field or window when clicked.

Thanks!
Robby

[vwphillips]

google

'linked select boxes'