Other types of definition are possible as well, taking into account not only organisms' phylogenetic relations and apomorphies but also whether or not related organisms are extant.
The draft of the PhyloCode has gone through several revisions. All older versions can be found . As of January 2020, the current version is 5, finalized January 2014 and released 21 January 2019.
As with other nomenclatural codes, the rules of the PhyloCode are organized as articles, which in turn are organized as chapters. Each article may also contain notes, examples, and recommendations.
As currently planned, however, the most important use of RegNum will be the decision of which one of a number of synonyms or homonyms will be considered accepted: the one with the lowest registration number, except in cases of conservation.
A list of published critiques of the PhyloCode can be found on the , as can a list of rebuttals.