The most useful thing I’ve managed today.
Subject: Abbreviations used in D&D Book titles ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AC - Accessory B - Basic CM - Companion DA - Dave Arneson DDA - Dungeons & Dragons Advanced GAZ - Gazeteer Series IM - Immortals M - Marker or Master Series O - One-on-one Scenarios PC - Player Character RPGA - RPG Association ST - Steam Train TM - Trail Map X - Expert