Published requirements for the EHR are principally available via ISO 18308. They are statements defining the generic features necessary in any Electronic Health Record for it to be communicable and complete, retain integrity across systems, countries and time, and be a useful and effective ethico-legal record of care. Examples of requirements are provided in four themes: EHR functional requirements; Ethical, legal, and security requirements; Clinical requirements; Technical requirements. The main logical building blocks of an EHR are described using the terminology of CEN TC251 ENV13606. Examples are given of the placement of attributes to satisfy contextual and other requirements at the level of specific building blocks. A worked example of the use of the building blocks is given for the request-report cycle for an imaging investigation.