Library of Congress >> MARC >> Bibliographic >> 00X >> 007 >> 007 (Microform)

007 - Microform (R)


MARC 21 Bibliographic - Full
October 2009

Indicators and Subfield Codes
Field has no indicators or subfield codes; the data elements are positionally defined.
Character Positions
00 - Category of material
h - Microform

01 - Specific material designation
a - Aperture card
b - Microfilm cartridge
c - Microfilm cassette
d - Microfilm reel
e - Microfiche
f - Microfiche cassette
g - Microopaque
h - Microfilm slip
j - Microfilm roll
u - Unspecified
z - Other
| - No attempt to code

02 - Undefined
# - Undefined

03 - Positive/negative aspect
a - Positive
b - Negative
m - Mixed polarity
u - Unknown
| - No attempt to code

04 - Dimensions
Microfilm
a - 8 mm.
d - 16 mm.
f - 35 mm.
g - 70 mm.
h - 105 mm.

Microfiche, Microopaque, etc.
l - 3x5 in. or 8x13 cm.
m - 4x6 in. or 11x15 cm.
o - 6x9 in. or 16x23 cm.

Aperture Card
p - 3 1/4 x 7 3/8 in. or 9x19 cm.

Other
u - Unknown
z - Other
| - No attempt to code


05 - Reduction ratio range
a - Low reduction ratio
b - Normal reduction
c - High reduction
d - Very high reduction
e - Ultra high reduction
u - Unknown
v - Reduction rate varies
| - No attempt to code

06-08 - Reduction ratio

09 - Color
b - Black-and-white
c - Multicolored
m - Mixed
u - Unknown
z - Other
| - No attempt to code

10 - Emulsion on film
a - Silver halide
b - Diazo
c - Vesicular
m - Mixed emulsion
n - Not applicable
u - Unknown
z - Other
| - No attempt to code

11 - Generation
a - First generation (master)
b - Printing master
c - Service copy
m - Mixed generation
u - Unknown
| - No attempt to code

12 - Base of film
a - Safety base, undetermined
c - Safety base, acetate undetermined
d - Safety base, diacetate
i - Nitrate base
m - Mixed base (nitrate and safety)
n - Not applicable
p - Safety base, polyester
r - Safety base, mixed
t - Safety base, triacetate
u - Unknown
z - Other
| - No attempt to code

FIELD DEFINITION AND SCOPE

When field 007/00 contains code h, it contains special coded information about the physical characteristics of microform material.


GUIDELINES FOR APPLYING CONTENT DESIGNATORS

CHARACTER POSITIONS

00 - Category of material
h - Microform
One-character alphabetic code that indicates the category of material to which the item belongs is microform. Microform is a generic term for any medium, transparent or opaque, bearing microimages. A microimage is a unit (e.g., a page) of textual, graphic, or computer-generated material that is contained on aperture cards, microfiche, microfilm, microopaques, or other microformats and that is too small to be read without magnification. Microforms may be reproductions of existing textual or graphic materials or they may be original publications. A fill character (|) is not allowed in this position.

01 - Specific material designation
Special class of microform to which the item belongs. (e.g., a microopaque).
a - Aperture card
Card with one or more rectangular opening(s), or aperture(s), specifically prepared for the mounting or insertion of a piece of photographic film containing one or more microimage(s). The cards are usually EAM (Electrical Accounting Machine) punched cards, commonly known as IBM cards, that are standardized for use in card-handling machines. Such cards contain only one aperture and most frequently have only one microimage.
b - Microfilm cartridge
Consists of a strip of photographic film wound onto a single core (or hub), housed in a protective container. Microfilm cartridges require reading equipment (readers and reader-printers) that is specifically adapted for their use. Normally, the end of the film is left free for threading into such equipment. Common film lengths, widths, and reduction ratios are the same as those of microfilm reels.
c - Microfilm cassette
Analogous to the sound tape cassette. Consists of a strip of photographic film wound onto a double core, housed in a protective container. Microfilm cassettes require reading equipment (readers and reader-printers) that is specifically adapted for their use. Because they are double-cored, they are not threaded when used in such readers and reader-printers. Usual film lengths are 100 ft (approximately 30 m.) or less. Common film width is 16 mm. and usual reduction ratios are those of microfilm reels and cartridges.
d - Microfilm reel
Consists of a strip of photographic film wound onto an unenclosed flanged holder (or reel). Microfilm reels require manual threading when used in readers and reader-printers and require equipment that is adapted for their use. Film lengths are usually 100 ft. (approximately 30 m.) or less. For microimages produced by filming textual and graphic materials, the most common film widths are 35 mm. and 16 mm. and reduction ratios commonly range from about 10:1 to about 20:1. Sixteen millimeter film with effective ratios of either 24:1 or 48:1 is most often used for COM (Computer-Output-Microfilm) microimages.
e - Microfiche
Transparent sheet of photographic film containing microimages arranged in a grid pattern (a two-dimensional array) and having a heading that contains identifying information in text that is large enough to be read without magnification. Grid patterns vary with reduction ratios.
Microfiches are grouped in five ranges of reduction ratios: low reduction (ratios up to and including 15:1), normal reduction (ratios greater than 15:1 up to and including 30:1), high reduction (ratios greater than 30:1 up to and including 60:1), very high reduction (ratios greater than 60:1 up to and including 90:1) and ultrahigh reduction (ratios greater than 90:1).
The most common microfiche are made by filming textual or graphic material at a reduction ratio of approximately 24:1. Such microfiche are 105 mm. high and 148 mm. wide (approximately 4x6 in.) and have a grid pattern that accommodates 98 microimages made from documents that are no more than 11 in. high and 8 1/2 in. wide. The heading area is the width of one row and is found directly above the first row of microimages.
The most common COM (Computer-Output-Microfilm) microfiche are made by recording computer-generated data at an effective reduction ratio of 48:1 on a 105 mm. x 148 mm. sheet of film. Such microfiche have a grid pattern of 15 rows and 18 columns, comprising 270 microimages. The heading area is the width of one row and is found directly above the first row of microimages.
Microfiche made at ultrahigh ratios are commonly called ultrafiche. Ratios and grid patterns have not been standardized for these microfiche and differ according to application and method for production.
f - Microfiche cassette
g - Microopaque
Sheet of opaque material bearing a number of microimages arranged in a two-dimensional array. Microopaques resemble microfiche. Common dimensions are 3x5 in. and 6x9 in. Common reduction ratios are approximately 24:1 or 20:1. Microopaques usually have identifying information in text that is large enough to read without magnification.
h - Microfilm slip
A short strip of microfilm cut from a roll.
j - Microfilm roll
A wound length of microfilm not on a reel, cartridge, etc.
u - Unspecified
Special material designation for the microform is not specified.
z - Other
None of the other codes is appropriate. Some microform types that use code z include:
Includes microforms such as microchips, microdots, and microform scrolls.
| - No attempt to code

02 - Undefined
Contains blank (#) or a fill character (|).

03 - Positive/negative aspect
Positive/negative polarity of the microform.
This characteristic is also referred to as the polarity.
a - Positive
Lines and characters appear dark against a light background.
Microopaques are always recorded as code a.
b - Negative
Lines and characters appear light against a dark background.
m - Mixed polarity
Mixture of positive and negative images.
u - Unknown
Polarity of the microform is not known. (Some colored negatives may appear to be positive if the colors of the original are not known.)
| - No attempt to code

04 - Dimensions
Dimensions of the microform; does not indicate the dimensions of the image.
For example, 16 mm. images on 35 mm. microfilm are coded f (35 mm.). Only the most common dimensions are indicated. Only codes that exactly match the measurement of the item as given in the physical description should be used. If no code exactly matches, code z is used.
The width of a microfilm is indicated in millimeters.
The height and width of a microfiche, microopaque, etc. are indicated in inches or centimeters. The first dimension is the height, the second is the width. The standard microfiche (105 mm. x 148 mm.) is coded m.
a - 8 mm.
d - 16 mm.
f - 35 mm.
g - 70 mm.
h - 105 mm.
l - 3x5 in. or 8x13 cm.
m - 4x6 in. or 11x15 cm.
o - 6x9 in. or 16x23 cm.
p - 3 1/4 x 7 3/8 in. or 9x19 cm.
Height and width of an aperture card in inches or centimeters.
u - Unknown
Dimensions are not known.
z - Other
None of the other codes is appropriate.
| - No attempt to code

05 - Reduction ratio range
Reduction ratio range for a microform. The specific reduction ratio is recorded in 007/06-08 (Reduction ratio).
For microfilm created by other than COM (Computer-Output-Microfilm) processes and for microopaque microprints, codes a and b are most likely to be used. For COM microfiche or microfilm, the reduction ratio is actually an expansion ratio and refers to the ratio of expansion required to produce a legible image. Most COM is created at 024-048 reduction ratios (codes b and c), though some COM fiche is at higher ratios (e.g., 072). Codes b-e are used with other types of microforms (e.g., microfiche, ultrafiche, etc.). The most commonly encountered microfiche are normal reduction (code b).
The reduction ratio is usually given on the microform itself. If it is not present, one must know the dimensions of the original item and the size of the image on the microform in order to code the information needed in 007/05.
a - Low reduction ratio
Less than 16:1 ratio (less than 016).
b - Normal reduction
Between 16:1 and 30:1 (016-030).
c - High reduction
Between 31:1 and 60:1 (031-060).
d - Very high reduction
Between 61:1 and 90:1 (061-090).
e - Ultra high reduction
Over 90:1 (over 090).
u - Unknown
Reduction ratio is not known.
v - Reduction rate varies
Not all parts of the microform have the same reduction ratio (e.g., the contents of two books may be microfilmed onto one piece of film; the type face on the books may differ, so that one of the books may be filmed at a 14:1 ratio and the other at a 18:1 ratio).
| - No attempt to code

06-08 - Reduction ratio
Number specifying the reduction ratio for a microform, recorded as three digits. The number is right justified and each unused position contains a zero (e.g., 015, 048). A hyphen is used for any unknown portion of the reduction ratio (e.g., 03-, 1--, or ---).
A code indicating the reduction ratio range is recorded in 007/05. Generally, the specific reduction ratio is recorded when it is ultra high (code e in 007/05). If the ratio is not ultra high, recording the specific ratio is less essential. Three fill character (|||) are used when no attempt has been made to code this data element.

09 - Color
Color of the image for microforms.
b - Black-and-white
Image is in black-and-white (usually black-and-transparent).
Includes only one color or hue other than black, for example, blue-and-white (blue-and-transparent). Always used for microopaques.
c - Multicolored
Has more than one color.
m - Mixed
Combination of one-color and multicolored images.
u - Unknown
Color of the microform is not known.
z - Other
None of the other codes is appropriate.
| - No attempt to code

10 - Emulsion on film
Type of light-sensitive material on the film.
Proper storage and use of microforms requires identification of the emulsion they contain.
a - Silver halide
Emulsion is a compound of silver and halogens. Silver halide microforms always appear black-and-white (black-and-transparent).
b - Diazo
Emulsion consists of sensitized layers composed of diazonium salts that react with couplers to form dye images. The color of the image is determined by the composition of the diazonium compound as well as the couplers used in the process and may be black, violet, or another color.
c - Vesicular
Light-sensitive component is suspended in a plastic layer. On exposure, the component creates optical vesicules (bubbles) in the layers. These bubbles form the latent image. The latent image becomes visible and fixed by heating the plastic layer and then allowing it to cool. Vesicular films are commonly blue or beige in color. They do not appear to have much contrast (very high density) until projected in a microform reader.
m - Mixed emulsion
For example, a microfilm may have slices of film with one type of emulsion and other slices with another type of emulsion.
n - Not applicable
Item does not have emulsion on film.
Used for microopaques.
u - Unknown
Emulsion on the film is not known.
z - Other
None of the other codes is appropriate.
| - No attempt to code

11 - Generation
Generation aspect of a microform.
a - First generation (master)
Camera master or COM recorder master.
Used for all master films that are made on archival stock in accordance with archival productions standards and that are given archival storage under relevant ISO standards.
b - Printing master
Any generation employed mainly for the production of other microforms.
Used for all masters that are not manufactured, produced, and stored in accordance with archival standards.
c - Service copy
Microform made from another microform that is intended primarily for use rather than for production of other microforms. Always used for microopaques.
m - Mixed generation
Made up of a combination of generations of film.
u - Unknown
Generation aspect is not known.
| - No attempt to code

12 - Base of film
Base of the film.
Safety base film is a comparatively nonflammable film base that meets the standard requirements for a safety base. On some film, the phrase safety base or a small equilateral triangle appears on the edge of microforms. Some microfilm produced overseas has similar notations in foreign languages. Vesicular and diazo microforms are always a safety base, as are silver halide microforms manufactured in the United States since approximately 1951. Nitrate film base is a highly flammable film base that does not meet the requirements for safety base film.
a - Safety base, undetermined
Type has not been identified.
c - Safety base, acetate undetermined
Acetate safety base film whose exact type cannot be determined, i.e., where it is unknown if the type is diacetate or triacetate.
d - Safety base, diacetate
Cellulose diacetate film base. Introduced before World War I for home movies, diacetate base was more expensive and unpredictable than nitrate base and so failed to gain acceptance in professional 35 mm. film production. Diacetate film base was at times used for microfilming of documents.
i - Nitrate base
Cellulose nitrate film. Cellulose nitrate support or base was used in the manufacture of 35 mm. film (and some 17.5 mm. film) until 1951. Nitrate base film is no longer manufactured. Nitrate film base was at times used for microfilming of documents.
m - Mixed base (nitrate and safety)
Combination of nitrate base and safety base film. The use of mixed bases, spliced together, can be found in microforms from the early 1950s.
n - Not applicable
Microform on a reflective rather than a transparent base.
Microopaques (which can be termed microcard or microprint) are an example of a microform not produced on a film base and are coded n.
p - Safety base, polyester
Film base is made of a synthetic resin (e.g., estar). During the 1980s, it became the most widely used base for microfilming of source documents.
r - Safety base, mixed
Mixed safety base films are spliced together; no nitrate film.
t - Safety base, triacetate
Cellulose triacetate film base. Cellulose triacetate is a high acetal compound with very low flammability and slow burning characteristics. From 1951, triacetate has been used for professional as well as for amateur produced moving image film. It has also been used at times for microfilming of documents.
u - Unknown
Base of film of the microform is not known.
z - Other
Bone of the other codes is appropriate.
| - No attempt to code

EXAMPLES

007 hd#bgc---cuuu
[Item is a microform (007/00); released as a microfilm reel (01); it has negative polarity (03); is 70 mm. (04); has a high reduction ratio (05); and is in color (09). Its emulsion (10), generation (11), and film base (12) are unknown.]
007 he#bmb024baca
[Item is a microform (007/00) (originally a printed work that has been filmed for reproduction in the microfiche format); released as a microfiche (01); has negative polarity (03); is approximately 4x6 in. (04); has a normal reduction ratio (05) of 24:1 (06-08); is monochromatic (09); has an emulsion of silver halide (10); is a service copy (11); and is on safety base film (12).]
007 hd#afa014bcaa
[Item is a microform (007/00) (a newspaper, filmed for reproduction); released as a microfilm reel (01); has positive polarity (03); is 35 mm. (04); has a low reduction ratio (05) of 14:1 (bytes 6-8); is monochromatic (09); has vesicular emulsion (10); is a service copy (11); and is on safety base film (12).]

INPUT CONVENTIONS

Field length - Field 007 for the category of material microform currently has thirteen character positions defined for it.

CONTENT DESIGNATOR HISTORY

007/01 - Specific material designation
h - Microfilm slip [NEW, 2009]
j - Microfilm roll [NEW, 2009]

007/02 - Original versus reproduction aspect [OBSOLETE, 1997] [USMARC only]
Defined codes were: f (Facsimile), o (Original), r (Reproduction), and u (Unknown).

007/12 - Base of film
b - Not safety base [OBSOLETE, 1991]
Code b was made obsolete when 007/12 for microforms was made consistent with the 007/12 (Base of film) for motion pictures and code i (Nitrate base) was defined.

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(11/12/2009)
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