mod:register({
    DataType = "MONUMENT",
    ...

--  Old
--  BuildingPartList = {
--      "MITHRIL_FACTORY_CORE_ROOT_PART",
--      "MITHRIL_FACTORY_EXTENSION_A_ROOT_PART",
--      "MITHRIL_FACTORY_EXTENSION_B_ROOT_PART",
--      "MITHRIL_FACTORY_DOOR_A_PART",
--      "MITHRIL_FACTORY_DOOR_B_PART",
--      "MITHRIL_FACTORY_DECORATION_A_PART",
--      "MITHRIL_FACTORY_DECORATION_B_PART"
--  },    

--  New
    BuildingPartSetList = {
        {
            Name = "PRODUCTION_CORE",
            BuildingPartList = {
                "MITHRIL_FACTORY_CORE_ROOT_PART"
            }
        },
        {
            Name = "PRODUCTION_EXTENSION",
            BuildingPartList = {
                "MITHRIL_FACTORY_EXTENSION_A_ROOT_PART",
                "MITHRIL_FACTORY_EXTENSION_B_ROOT_PART"
            }
        },
        {
            Name = "ENTRANCE",
            BuildingPartList = {
                "MITHRIL_FACTORY_DOOR_A_PART",
                "MITHRIL_FACTORY_DOOR_B_PART"
            }
        },
        {
            Name = "DECORATION",
            BuildingPartList = {
                "MITHRIL_FACTORY_DECORATION_A_PART",
                "MITHRIL_FACTORY_DECORATION_B_PART"
            }
        }
    },
    
    ...
})