IEC 61300-1:2011 contains a series of environmental test and measurement procedures and, in some cases, preferred severities designed to assess the ability of fibre optic interconnecting devices and passive components to perform under expected service conditions. Although the severities are primarily intended for land-based communications, the procedures may be used for other applications. The object of this standard is to provide uniform and reproducible environmental test procedures and measurement procedures, for those preparing specifications for fibre optic interconnecting devices and passive components. The changes with respect to the previous edition are to reconsider the terms and definitions and multimode launch conditions.