can_be_kurultai_trigger

can_be_kurultai_trigger = {
	can_be_councillor_basics_trigger = yes
	exists = $COURT_OWNER$
	NOT = { government_has_flag = government_is_herder }
	NOR = {
		has_council_position = councillor_spouse
		has_court_position = court_astrologer_court_position
		AND = {
			this = $COURT_OWNER$.diarch
			$COURT_OWNER$ ?= { has_diarchy_active_parameter = diarchy_is_vizierate }
		}
	}
	NOR = {
		has_council_position = $CP1$
		has_council_position = $CP2$
		has_council_position = $CP3$
	}
	OR = {
		is_landed = yes
		is_knight_of = $COURT_OWNER$
		is_courtier_of = $COURT_OWNER$
		is_ruler = yes
		is_powerful_vassal = yes
	}
	OR = {
		is_ruler = yes
		AND = {
			is_female = yes
			$COURT_OWNER$.rite = { NOT = { rite_has_parameter = male_dominated_council } }
		}
		AND = {
			is_male = yes
			$COURT_OWNER$.rite = { NOT = { rite_has_parameter = female_dominated_council } }
		}
		AND = {
			has_trait = shieldmaiden
			$COURT_OWNER$.culture = { has_cultural_parameter = has_access_to_shieldmaidens }
		}
	}
}

As written in game/common/scripted_triggers/00_councillor_triggers.txt.