[Zope] how to get started with Zope development?

hi, i'm a newbie and started making a site with zpt on Zope. i've been trying to read over various documents and helps and specs from various sites. but when i get across example codes from this list or some other sources, time to time, i'm discouraged by new functions, modules and usages. the product PythonScripts is one of them. today i found 'bobobase_modification_time' from an example code, but it's not in the API reference or python built-in functions. i wanna know what is the proper approach to Zope development? should i look into Zope source code or something? thanks, hwan