This Singapore Standard specifies the operating procedures for imaging and writing of digital text and drawing documents on 16 mm and 35 mm black and white, silver-gelatin type microfilm for long term preservation.\nIn this Singapore Standard, long term is considered to be a period of time usually lasting more than a century. In ISO 18911, the life expectancy (LE) is the length of time that information is predicted to be acceptable in a system at 21℃ and 50% RH. The number following the LE symbol is a prediction of the minimum life expectancy, in years, during which information can be retrieved without significant loss when stored at 21℃ and 50% RH, e.g. LE-100 indicates that information can be retrieved after at least 100 years' storage. Broadly speaking, extended-term storage conditions can extend the useful life of a majority of freshly processed films to 500 years.\nBlack-and-white, silver-gelatin type microfilm when properly processed and stored will become an irreversible record of proven quality, meeting extended-term storage criterion.\nThis Singapore Standard does not cover the following:\n- Animated images or sounds;\n- Three-dimensional images; and\n- Electronic medical records such as X-ray images.