A National minimum data set (NMDS) is a minimum set of data elements agreed for mandatory collection and reporting at a national level. It may include data elements that are also included in other NMDSs. An 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.
A data set specification (DSS) is a metadata set that is not mandated for collection but is recommended as best practice.
From 2016-17 onwards, a decision was taken by the Health Registration Authority to re-categorise the health sector DSSs as either best endeavours or best practice.