International Code of Phylogenetic Nomenclature (PhyloCode)

Division I. Principles

1. Reference. The primary purpose of taxon names is to provide a means of referring to taxa, as opposed to indicating their characters, relationships, or membership.

2. Clarity. Taxon names should be unambiguous in their designation of particular taxa. Nomenclatural clarity is achieved through explicit definitions that describe the concept of the taxon designated by the defined name.

3. Uniqueness. To promote clarity, each taxon should have only one accepted name, and each accepted name should refer to only one taxon.

4. Stability. The names of taxa should not change over time. As a corollary, it must be possible to name newly discovered taxa without changing the names of previously discovered taxa.

5. Phylogenetic context. This code is concerned with the naming and subsequent application of the names of phylogenetically conceptualized taxa.

6. Taxonomic freedom. This code does not restrict freedom of opinion with regard to hypotheses about relationships; it only concerns how names are to be applied within the context of any relevant phylogenetic hypothesis.

7. There is no “case law” under this code. Nomenclatural problems are resolved by the Committee on Phylogenetic Nomenclature (CPN) by direct application of the code; previous decisions will be considered, but the CPN is not obligated by precedents set in those decisions.