HSE's Operations Notice 27
The move from a regime of prescriptive to goal-setting regulations in 1996 led to the withdrawal of the technical information contained in the Offshore Installations (Construction and Survey) Regulations 1974 (SI 1974/289) which was generally referred to as the Fourth Edition. The HSE published Operations Notice 27: http://www.hse.gov.uk/offshore/notices/on_27.htm to explain how the industry could continue to use this information.
Where still technically adequate, that guidance has been made available as individual research reports in HSE's Offshore Technology (OTO) series. These are included in Level 3 with a comment to indicate that they are a valid reference in Operations Notice 27. As a note of caution, users should be aware that these research reports are not updated.
Note that whilst other HSE research reports might provide valuable insight or direction, they do not reflect HSE policy; therefore, their guidance is 'not approved' and their content shall not be considered as technical justification. Consequently only those OTO research reports specifically noted in Operations Notice 27 are included in the Catalogue.