Microform includes both film and fiche. Microfilm comes in roll
form. It was developed more than 100 years ago as a part of
conventional photographic technology. Early microfilm seems to
have been generally stable. If microfilm has a quality polyester
film base, is exposed and processed to international standards,
is housed in stable protective enclosures, and is stored under
the appropriate conditions, it will last for a minimum of 500
years. The longevity issue is vitally important, as it
delineates the main difference between microfilm and other
reformatting technologies such as digital imaging. Microfiche
usually replicates multiple individual pages in single fiche
sheets. It can be made up of strips of film cut from rolls and
placed in polyester jackets, or made by filming with a "step and
repeat" camera, with images imposed directly onto a single sheet
of film. Microfilm is available in 16 or 35 millimeter widths
with 35 millimeters the norm for preservation filming. Microform
is now available as silver