ISO 5459:2011 specifies terminology, rules and methodology for the indication and understanding of datums and datum systems in technical product documentation. It also provides explanations to assist the user in understanding the concepts involved. ISO 5459:2011 defines the specification operator (see ISO 17450-2) used to establish a datum or datum system. The verification operator (see ISO 17450-2) can take different forms (physically or mathematically) and is not the subject of ISO 5459:2011. The detailed rules for maximum and least material requirements for datums are given in ISO 2692.