IEC 61274-1:2011 applies to fibre optic adaptors for all types, sizes and structures of optical fibre connectors. It includes: - adaptor requirements; - quality assessment procedures. This standard does not cover test and measurement procedures, which are described in the IEC 61300 series. This third edition cancels and replaces the second edition published in 2007, and constitutes a technical revision. The specific technical changes from the previous edition include removal of quality assessment procedure, to add the definition of plug-socket configuration, to reconsider a drawing showing the relationship between IEC 60874, IEC 61753, IEC 61754 series of standards, and updating the normative references.