From the Back of the Book:
A COMPILATION OF six years of detailed research, The BattleTech Compendium may well be the ultimate resource for the player. Clear and concise rules clarifications, battle demonstrations, and rules changes will help develop and streamline play. All the material from The Battletech Manual is presented in revised form, as well as additional rules for JumpShip and DropShip combat, 'Mech construction, and the latest discoveries concering the technology of the Star League and the invading Clans. Optional rules are included for miniature play, environmental effects on the battlefield, and more. Loaded with color photos, this Compendium gives the clearest picture yet of combat in the 31st century.
on the BGG domain The BattleTech Compendium