This part of IEC 60695 gives guidance on: a) the optical measurement of obscuration of smoke; b) general aspects of optical smoke test methods; c) consideration of test methods; d) expression of smoke test data; e) the relevance of optical smoke data to hazard assessment. This basic safety publication shall be used by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51. One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications.