I have to say I also used these includes one of the main features in the heart of them was they would remove any duplicate code etc from the included files so extra HEAD BODY etc tags plus more complex duplicated code was removed to make them very stable.
Also:
Include from Table
Include from List
Extremely powerful and make life so easy.
Ie for the second of those you could basically create a single page and just include depending on the URL Parameter.
ch13_reuse_content_1.html
Ironically the ADDT docs point to the old Interakt Docs :)