Very occasionally you may come across a plant with a third name, which has no indication of rank. This is known as a trinomial. Names of this sort are most often seen in old or historic publications; using them was once common practice, but under the Botanical Code these names, if originally published as such, are invalid. However, a few are still found in listings of plant names, usually where the rank of the third name is unknown; this is an unsatisfactory situation and it may be best to treat such names as cultivar epithets (see below) until they can be resolved.