Nomenclature of Organic Chemistry, commonly referred to by chemists as the Blue Book is a collection of recommendations on organic chemical nomenclature published at irregular intervals by the International Union of Pure and Applied Chemistry (IUPAC). The last full edition was published in 1979,[1] although an abridged and updated version was published in 1993 as A Guide to IUPAC Nomenclature of Organic Compounds.[2] Both of these are now out-of-print in their paper versions, but are available free of charge in electronic versions. A fully revised edition is planned, of which a draft version was released for public comment in 2004.[3] In the meantime, several sections have been revised and published in the journal Pure and Applied Chemistry.