olemus
ISO/IEC 24765, ISO/IEC Guide 2:2004:
normdokumendi nõue, mis peab sellele dokumendile vastavuseks olema tingimata täidetud
= requirement of a normative document that must necessarily be fulfilled in order to comply with that document

ISO/IEC Guide 2, Note:
The term “mandatory requirement” should be used to mean only a requirement made compulsory by law or regulation.