This part of IEC 62149 covers the performance specification for 850-nm discrete vertical cavity surface emitting laser (VCSEL) devices of transverse multimode types used for the fibre optic telecommunication and optical data transmission application. The performance standard contains a definition of the product performance requirements together with a series of sets of tests and measurements with clearly defined conditions, severit ies, and pass/fail criteria. The tests are intended to be run on a “once-off” basis to prove any product’s ability to satisfy the performance standard’s requirements.