Rationale

This work item is to address issues with the Verification of  Apparatus (10) and Verification of Apparatus Performance. (Annex A4). This will aim to clarify the creation, use and application of Certified Reference Materials(CRM) and Secondary Working Standards (SWS) as well as broadening the use of  listed pure materials and materials from approved Proficiency Testing Programs (PTP). D93 is officially aligned with IP 34 (EN ISO 2719) and similar revisions are under development in the Energy Institute and ISO.