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Structured Glossary of Technical Terms–

Commission on Preservation and Access


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The Original Document
1.1 Medium
1.2 Format
1.3 Periodicity
1.4 Properties
1.5 Condition
1.6 Content
1.1. Document Medium
Document Medium refers to the material upon which the original document
was recorded.
1.1.1. Paper
Paper is a medium traditionally used for printed books and
other documents that are the most frequent target of preservation efforts.
Paper is defined to be sheets usually made of vegetable fibers laid
down on a fine screen from a water suspension. Marks are imprinted
on the paper using any of a number of techniques including handwriting or drawing using
a variety of media such as pencil, pen and ink, or pastel; various
forms of printing
using inks (numerous technologies are used to
accomplish this); photographic printing, where paper coated
with light-sensitive emulsion is exposed to various intensities of
light); xerographic printing, where an electrically charged photoconductive
insulating surface is selectively exposed to light and the latent image
is developed with a resinous powder; thermographic printing,
where the paper is exposed to a directed heat source that selectively
modifies parts of the surface that may have been pre-treated with a
heat-sensitive powder; and chemical transfer printing, where
the surface of the paper is chemically coated and selectively modified
by pressure or other means.Parchment and vellum are not paper since they are
made from the skins of sheep, goats, or calfskin. 7 We note them here for completeness.Hard Copy is a term often used to denote any document produced
on paper.
1.1.2. Microform
Microform refers to a document medium for producing or reproducing
printed matter. It records microimages, that is, images too
small to be read without some form of magnification. In a general sense,
microforms may be on film (1.1.4) or paper (1.1.1),
but for purposes of this Glossary the definition is restricted to film.
Reading a microform requires the assistance of a microform reader (
Microform comes in different styles including microfilm (a
film roll that contains microimages arranged sequentially) and microfiche (sheets
of film in which many microimages are arranged in a grid pattern).
Both usually contain a header that can be read without magnification).Microforms are an economic and compact form of document representation
for archival storage, but are inconvenient to read when compared with
a printed book. Microform technology is used as a preservation medium
(3.1.4), as a means of saving
space (such as for the convenient storage of newspapers), or as a means
of duplicating scarce or unique documents, that is, microreproductions
of other original documents. However, microform is sometimes used for
original documents, for example, those created on a computer and directly
printed out onto a computer-output-on-microfiche (COM) device;
and for microreproductions of material assembled for the purposes of
releasing an original edition in microform.
1.1.3. Video
Video is normally an analog (see definition under 1.1.6) electronic
technology for recording still or moving images, usually combined with
sound (cf. 1.1.5). Following standards (which vary across the world)
defined for television playback and broadcasting, the images are normally
recorded on magnetic tape (,
when it is known as videotape, but also on other physical
media such as optical disk (
(videodisk).Playback is usually achieved through a television set or video projector
(, although it is now
possible and becoming common to play video recordings back through
a computer ( or multimedia
workstation (
1.1.4. Film
Film is a recording medium consisting of thin sheets or strips
of transparent or translucent material, such as polyester or acetate,
coated with a light-sensitive emulsion. Recording occurs by exposing
the film to the light emitted or reflected by the entity being recorded.
Film is also the medium used for microfilm recording (1.1.2).
A photograph ( is produced using essentially
the same technology, except that normally the light- sensitive emulsion
is adhered to paper or some other opaque medium.
1.1.5. Audio
Audio documents are recordings made on a variety of (usually)
magnetic media (see
of sounds only (as contrasted with video recordings (1.1.3)
that also combine images). The evolution of such audio recordings has
traversed a large number of different formats and physical media, including phonograph disks
(records) of varying size (78 rpm’s. 45 rpm’s, 33 rpm’s) and tape
(of different formats), both of which are analog (see 1.1.6)
recording technologies; and, more recently, compact disks and digital
acoustic tapes (DATs)
, which are digitally (1.1.6)
1.1.6. Digital Electronic
Digital Electronic Technologies 8 are
technologies used to capture (3.2.3),
store (, transform (3.3.2, 3.3.4, 3.3.2, 3.3.4),
distribute ( or present
information in quantized electronic form (normally as a sequence of
O’s and l’s known as bits). Digital, in which information
is quantized discretely, is to be contrasted with Analog,
in which information is not quantized but maintained in a continuous
format. 9 A video recording (1.1.3),
is an example of an electronic technology that is analog 10.For a variety of reasons, digital technologies are gradually replacing
analog technologies. Reasons of importance to this Glossary are the
convertibility of digital technologies among each other and into and
from other technologies (such as paper and voice), so that digital
technologies become a kind of lingua franca of communication
and storage; and the ease of transmission of information by digital
technologies across networks (3.5.5)
to facilitate communication at a distance.Original documents that are of concern for library preservation purposes
are not normally encoded in a digital electronic medium. 11 Since this may become a subject of future
concern, the category is included for completeness. Definitions, however,
are more appropriately included under Storage Technology Medium ( Magnetic Disk (see Magnetic Tape (see Optical Disk (see Optical Tape (see Magneto-Optical Disk (see
1.1.7. Multi-Media
Multi-Media is a term used to denote documents created using
a number of different media simultaneously, usually those with an electronic
technological basis: for example, a digital electronic recording (1.1.6)
that also combines video (1.1.3)
and audio (1.1.5), and that may,
as part of the document, intrinsically produce paper (1.1.1)

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