Related Rule
Colombia
Practice Relating to Rule 106. Conditions for Prisoner-of-War Status
Colombia’s Instructors’ Manual (1999) states:
Combatants must distinguish themselves from the civilian population when they participate in combat action or in an operation preparatory thereto. Members of regular Armed Forces normally wear their uniform. Members of other militias, such as rebels and guerrillas, use a distinctive sign and normally carry their arms openly. 
Colombia, Derechos Humanos & Derecho Internacional Humanitario – Manual de Instrucción de la Guía de Conducta para el Soldado e Infante de Marina, Ministerio de Defensa Nacional, Oficina de Derechos Humanos, Fuerzas Militares de Colombia, Santafé de Bogotá, 1999, p. 16.
At the CDDH, Colombia abstained in the vote on Article 42 of the draft Additional Protocol I (now Article 44) because it lacked precision and did not safeguard the civilian population sufficiently. 
Colombia, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.41, 26 May 1977, p. 181.