Aperture card

Such a card is used for archiving or for making multiple inexpensive copies of a document for ease of distribution.

[1] The microfilm chip is most commonly 35mm in height, and contains an optically reduced image, usually of some type of reference document, such as an engineering drawing, that is the focus of the archiving process.

Machinery exists to automatically store, retrieve, sort, duplicate, create, and digitize cards with a high level of automation.

They have a 500-year lifetime, they are human readable, and there is no expense or risk in converting from one digital format to the next when computer systems become obsolete.

Handling physical cards requires proprietary machinery and processing optical film takes significant time.

Faded drawings or those of low or uneven contrast do not reproduce well and significant detail or annotations may be lost.