From the back of the book:
"To maintain their monopoly on the flow of information and technology across the vast reaches of space, the powerful organization known as ComStar waged a hidden war of assassination, sabotage and terrorism for more than two hundred years. Now, the Star League has been resurrected and ComStar will play a pivotal role in its continued survival... or its ultimate downfall.
BattleTech Field Manual: ComStar describes the military doctrine, traditions, tactics and battle histories of ComStar's military division, the Com Guards, and the Word of Blake splinter group. This book also provides complete information on the Free Rasalhague Republic and units of the new Star League, including the Eridani Light Horse and Clan Nova Cat, plus new equipment and 'Mechs unique to ComStar."