The threatened species categories used in Red Data Books and Red Lists have been in place for almost 30 years. The Red Data Book categories provide an easily and widely understood method for highlighting those species under higher extinction risk, so as to focus attention on conservation measures designed to protect them. This document, incorporating changes recommended by IUCN members, was adopted by the IUCN Council in 1994.
From title page: IUCN Red List Categories as approved by the 40th meeting of the IUCN Council, 30 November 1994. This is version 2.3 of the document. Language versions issued separately. Russian version published by Ekotsyentr, Karaganda, 1997. Also available in HTML format.