Around 2000 I have created an illustrated list of Global GDL parameters and Zone Fix Parameters for Graphisoft. These are still available on the old ArchiCADWiki site:
https://195.144.20.131/Global%20GDL%20Parameters
https://195.144.20.131/Zone%20Fix%20Parameters
I would love to see something similar (detailed info with illustrations) and updated for the latest versions. When these were first created the latest version was 6.5.
Laszlo Nagy
ARCHICAD-TALK Moderator, Site Admin