Forgotten Realms
The "Campaign Set" (often referred to as the "Grey Box") was later released in 1987 as a boxed set of two source books ("Cyclopedia of the Realms" and "DM's Sourcebook of the Realms") and four large maps, designed by Greenwood in collaboration with author Jeff Grubb. The set introduced the campaign setting and explained how to use it, and reserved space on the map for SSI's Gold Box computer role-playing games set in the Forgotten Realms.
Forgotten Realms Campaign Setting
A number of changes have been made since the previous books were published by the former TSR, Inc. The most important update has been the inclusion of the 3rd edition's significant revisions to the game system. Various regional feats, character attributes, prestige classes, spells and non-player character statistics use the new rule set.