International Union for Conservation of Nature and Natural Resources Red List of Threatened Species Classification Schemes

"In order to ensure global uniformity when describing the habitat in which a taxon occurs, the threats to a taxon, what conservation actions are in place or are needed, and whether or not the taxon is utilized, a set of standard terms (called Classification Schemes; formerly referred to as Authority Files) have been developed for documenting taxa on the IUCN Red List. These Classification Schemes are still being developed and tested and not all of them have been implemented in this version of the IUCN Red List."