A Trinary is a common formation of Clan military forces which consists of three Stars, making it equivalent to a reinforced company in the Inner Sphere. Requiring only a modest increase in logistical support over a Star, Trinaries are among the most common military deployments fielded by the Clans. A Trinary can either be "pure," consisting of three stars of the same unit type, or "mixed," consisting of three Stars of different unit types; both are used by all Clans, with the former having a slight edge in numbers. Trinaries are commanded by a Star Captain.
A 'Mech Trinary consists of fifteen OmniMechs or BattleMechs and while sometimes organized by weight class, they will just as often contain Stars of mixed weight types. Thirty OmniFighters or AeroSpace Fighters, commonly of mixed designs and weight classes, make up an aerospace Trinary, while between fifteen to eighteen vessels make up a naval Trinary. An armor Trinary also consists of thirty Combat Vehicles, though the Clans' disregard for conventional armor makes these units rare outside conventional Clusters. Infantry Trinaries consist of seventy-five Battle Armored Elementals and while theoretically possible few Clans ever organize conventional infantry at this level.
Mixed Trinaries are only slightly less prevalent than pure formations among the Clans, the most common type being a pair of 'Mech Stars and an Elemental Star. Clan Snow Raven deploys a variant of the mixed Trinary known as a Triad that consists of one Star each of 'Mechs or vehicles, Elementals or Infantry and Aerospace Fighters. A Supernova Trinary is a special type of Trinary which combines three Novas.
- MechWarrior's Guide to the Clans, p. 75
- Field Manual: Warden Clans, p. 12
- Field Manual: Crusader Clans, p. 10
- Field Manual: Warden Clans, p. 10
- Field Manual: Crusader Clans, p. 8
- Field Manual: Warden Clans, p. 11
- Field Manual: Crusader Clans, p. 9
- Field Manual: Warden Clans, p. 123