This Guidance Note explains aspects of the past and current policy for the inclusion in the EPSG Dataset of so-called null coordinate transformations to WGS 84 and limitations in the description of WGS 84 through coordinate reference system code EPSG:4326. It also describes the application of datum ensembles in the EPSG Dataset and recommends appropriate usage of this data. The Guidance Note is aimed at application developers, data managers, operational surveyors, and GIS end-users requiring decimetre to ~1-3m accuracy, especially those working in the oil, gas, and renewables industries, both in operating companies and for contractors/service providers.