Passable Relations by Ron Newcomb begins here.

"Allows us to ask if an abstract relation holds between two objects. Supports the standard physical relations as well as any new relations."

• Volume - Extension Passable Relations
• Chapter 1 - Most useful phrases
• Chapter 2 - The printing a relation activity
• Chapter 3 - Definitions
• Chapter 4 - VM differences
• Section 1 - uses indexed text (for Glulx only)
• Section 2 - avoids indexed text (for Z-machine only)
• Chapter 5 - Hide this mess from the documentation - unindexed
• Chapter 7 - Hard-bitten Inform 6 datacode