FDN: Nicaraguan Democratic Force. The main contra military group, based in Honduras and made up of 10,000 to 12,000 men, according to informed estimates. UNO: United Nicaraguan Opposition. The main contra political organization, made up of the FDN, Kisan (a Miskito group, see below), and some former members of ARDE (see below). Headed by Adolfo Calero, Arturo Cruz, and Alfonso Robelo. BOS: Southern Opposition Bloc. A Costa Rican-based political organization that considers itself social democratic. Headed by Alfredo C'esar. It commands only a handful of troops. Kisan: A Miskito Indian political-military organization created in September 1985, and now commanding an estimated 500 troops. Another 500 Kisan guerrillas are abiding by a cease-fire while their leaders negotiate with the Nicaraguan government. ARDE: Democratic Revolutionary Alliance. A now defunct political-military group. Headed by former Sandinista Ed'en Pastora G'omez, until he withdrew from fighting in May 1986. The few remaining troops now fight for the Southern Opposition Bloc. UNO-FARN: UNO-Nicaraguan Revolutionary Armed Forces. UNO's quiescent southern front, consisting of several hundred men loyal to Fernando Chamorro, titular chief of FARN. Misurasata: A Miskito Indian political-military group, which refused to join UNO. Headed by Brooklyn Rivera, its estimated 1,000 guerrillas have not engaged in fighting for more than 18 months.