[tmtvl]

You probably mean The Craft of Text Editing -or- A Cookbook for an Emacs. I've skimmed it a bit before and it's on my reading list. First I'm still working my way through CRLS's Introduction to Algorithms and Aspnes' Notes on Data Structures and Programming Techniques.

[bloopernova]

Links to the electronic versions of this out of print book: https://www.finseth.com/craft/