What all are the elements in an Autosar DEXT ARXML file and the "check rules" after creating a DEXT?

I am trying to contribute to an open-source python code in git which creates a DEXT ARXML file from a set of inputs (doc, xls). I want to know/ get a list of elements that SHOULD be in it and all a similar list of all the "checking rules". I would like to build a checker module also.

I've started reading the R23-11 version of the following documents:

• Autosar TPS DEXT document but it is 700 odd pages and is taking more time than I can manage.
• XML schema production rules. Got the XSD for a generic ARXML from autosar website. I can use this to create the structure for the DEXT's ARXML.
• XML serialization rules.