I cannot seem to find where extensions are created... I created an extension 1000 and I cannot seem to find that extension in one of these config files. I get it you are one of those RTFM type guys... and I understand that but there is also something to be said of a forum where users exchange knowledge.
I previous versions of Asterisk I have worked with the extensions are stored in extensions.conf.. not sure where else to look. Perhaps I will have better luck with the Trix branded options.
I am indeed a RTFM kind of guy, I will do that for you as I guess you missed the important bits as you "looked through" the link and 238 pages is indeed a "huge" amount of probably largely irrelevant information , look at the line in extensions.conf that says very specifically
Then look at that included file.
(that syntax has been in Asterisk configuration since the year dot)
You are perhaps confusing the difference between an extension and the provisioning of that extension, (This post was named "Extensions" ), refer to my other post for the SIP bit, or IAX2 etc. if the extension of which you speak is provisioned with some other protocol.