Reduction of images is 24x, 48x, or 90x. Rectangular shaped cards with individual frames of 33mm film mounted by adhesive tape or inserted into transparent sleeves. Some cards are punched in a manner to make them machine-readable. Jacketing microfilm is a process that takes roll film and places it into fiche format. Jackets are usually made of transparent plastic divided into strips which accommodate the size of the film.
Jackets allow for the insertion of documents into a filmed file.
Whichever microform is selected, the most important rule to follow is consistency. All the microforms have advantages and disadvantages. Careful consideration when selecting the microform needs to be given to filming, processing, and reproduction facilities available to the Agency. Contact NARA or refer to the latest NARA Bulletin for information on reimbursable micrographic services, procedures, and fees. After microfilming, disposition of both the paper and microfilm record must be made in accordance with the requirements of the approved Bureau of Reclamation records retention schedules, and applicable policies and standards.