HyTime was Kimber’s work, and I found this reflections of his on “worse is better” to be quite refreshing, especially when contrasting the formality of SGML against the flexibility of HTML.

https://drmacros-xml-rants.blogspot.com/2010/08/worse-is-bet...

I’ll have to spend more time in the SGML Handbook. It’s available for borrowing at https://archive.org/details/sgmlhandbook0000gold. So far, I’ve been focused on the spec and trying to understand the intent behind the rules.

> a couple of auxiliary conventions introduced to make attribute capture and mapping in link rules more useful

Do you have any pointers on how to find these in the spec or in the handbook? Some keywords? What I’ve gathered is that notations point to some external non-SGML processor to handle the rendering and interpretation of content, such as images and image-viewing programs.

Cheers!