I'd like to create custom ajax-driven inputfield. Ajax-driven inpufields where introduced here: http://processwire.com/blog/posts/new-ajax-driven-inputs-conditional-hooks-template-family-settings-and-more/#new-ajax-driven-inputfields-system-wide, but since that time I haven't seen any "how-to" tutorials. I'd like to learn from core code, but can't understand which files to check.
Can someone suggest which core/module files I have to check in order to learn from code and be able to create custom ajax-driven inputfields?