See Address Family Numbers and Subsequent Address Family Identifiers (SAFI) Values registries.
Address Families and Subsequent Address Families must not be directly added to the iana-routing-types YANG module. They must instead be respectively added to the [Address Family Numbers] and [Subsequent Address Family Identifiers (SAFI) Parameters] registries. Module: [iana-routing-types@2020-12-31.yang]