 Cahn–Ingold–Prelog priority rules

The Cahn–Ingold–Prelog (CIP) sequence rules, named for organic chemists Robert Sidney Cahn, Christopher Kelk Ingold, and Vladimir Prelog — alternatively termed the CIP priority rules, "system", or "conventions" — are a standard process used in organic chemistry to completely and unequivocally name a stereoisomer of a molecule.The purpose of the CIP system is to assign an to each stereocenter and an "E" or "Z" descriptor to each double bond so that the configuration of the entire molecule can be specified uniquely by including the descriptors in its systematic name.