create_cadet_house_with_name_effect

create_cadet_house_with_name_effect = {
	add_achievement_flag_effect = { FLAG = achievement_a_house_of_my_own_flag }
	house.house_head = {
		save_scope_as = former_house_head
	}
	house = {
		save_scope_as = former_house
	}
	save_scope_as = new_head
	save_scope_as = new_house_head # don't ask
	save_best_location_for_house_name_effect = yes

	if = { # Prefixed Primary Title - (PREFIX) (TITLE)
		limit = {
			is_landed = yes
			highest_held_title_tier <= tier_duchy
			OR = {
				culture = { has_cultural_pillar = heritage_frankish }
				top_liege = {
					has_title = title:k_france
					culture = { has_cultural_pillar = heritage_frankish }
				}
			}
		}
		create_cadet_branch = {
			prefix = dynnp_de
			name = cadet_name_style_primary_title
			save_scope_as = new_house
		}
	}
	else_if = { # Barony Dynasty - (BARONY) (DYNASTY)
		limit = {
			culture = {
				OR = {
					culture_uses_barony_dynasty_names_trigger = yes
					culture_uses_barony_dynasty_names_only_branch_trigger = yes
				}
			}
		}
		create_cadet_branch = {
			name = cadet_name_style_barony_dynasty
			save_scope_as = new_house
		}
		scope:new_house ?= { generate_coa = yes } # Avoid western style cadet CoA
	}
	else_if = { # County Dynasty - (COUNTY) (DYNASTY)
		limit = {
			culture = { culture_uses_county_dynasty_names_only_branch_trigger = yes }
		}
		create_cadet_branch = {
			name = cadet_name_style_county_dynasty
			save_scope_as = new_house
		}
		scope:new_house ?= { generate_coa = yes } # Avoid western style cadet CoA
	}
	else_if = { # Japanese - (PLACE)
		limit = {
			culture = { culture_uses_japanese_dynasty_names_trigger = yes }
		}
		create_cadet_branch = {
			name = {
				first_valid = {
					triggered_desc = {
						trigger = { scope:new_head.var:new_japanese_house_name ?= flag:japanese_house_random_barony }
						desc = japanese_house_random_barony
					}
					triggered_desc = {
						trigger = { scope:new_head.var:new_japanese_house_name ?= flag:japanese_house_primary_county }
						desc = japanese_house_primary_county
					}
					triggered_desc = {
						trigger = { scope:new_head.var:new_japanese_house_name ?= flag:japanese_house_domicile_barony }
						desc = japanese_house_domicile_barony
					}
					triggered_desc = {
						trigger = { scope:new_head.var:new_japanese_house_name ?= flag:japanese_house_domicile_county }
						desc = japanese_house_domicile_county
					}
					triggered_desc = {
						trigger = { scope:new_head.var:new_japanese_house_name ?= flag:japanese_house_first_name }
						desc = japanese_house_first_name
					}
					triggered_desc = {
						trigger = { scope:new_head.var:new_japanese_house_name ?= flag:custom }
						desc = japanese_house_name_custom
					}
					triggered_desc = {
						trigger = { exists = scope:new_head.var:new_japanese_house_name }
						desc = japanese_house_name_flag
					}
					desc = japanese_house_name_fallback
				}
			}
			save_scope_as = new_house
		}
		scope:new_house ?= { generate_coa = yes } # Avoid western style cadet CoA
	}
	else = { #Standard Name Generation
		create_cadet_branch = { save_scope_as = new_house }
	}
}

As written in game/common/scripted_effects/00_decisions_effects.txt.