A National Minimum Data Set (NMDS) is a core set of data elements agreed by the National Health Information Management Group for mandatory collection and reporting at a national level. One NMDS may include data elements that are also included in another National Minimum Data Set. A NMDS is contingent upon a national agreement to collect uniform data and to supply it as part of the national collection, but does not preclude agencies and service providers from collecting additional data to meet their own specific needs.The National Health Data Dictionary contains definitions of data elements that are included in NMDS collections in the health sector, including data elements used to derive some of the performance indicators required under Australian Health Care Agreements (bilateral agreements between the Commonwealth and State/Territory governments about funding and delivery of health services).The following pages contain the Emergency department waiting times NMDS and its associated data elements and data element concepts.