[NTG-context] Documentation/tutorial for xml.collected, xml.first etc.?

I am trying to find documentation for the xml interface in lua. Explanation/tutorial for the use of functions like xml.first, the ‘.’ interface, etc. I see examples of their use but not everything is immediately clear to me. Gerben Wierda Chess and the Art of Enterprise Architecture https://ea.rna.nl/the-book/ Mastering ArchiMate https://ea.rna.nl/the-book-edition-iii/ Architecture for Real Enterprises https://www.infoworld.com/blog/architecture-for-real-enterprises/ at InfoWorld On Slippery Ice https://eapj.org/on-slippery-ice/ at EAPJ