Field 007 for microforms provides coded information for original and reproduction microforms.  The field is repeatable; elements within it are not.  Field 007 is repeatable for representing in one record:  1) a preservation master negative, printing master, and service copy that are created from one filming operation, and 2) positive and negative service copies produced by the same micropublisher.  When more than one 007 field is input, give in the following order:

1st 007 = service copy 11/$i = c

2nd 007 = 1st generation master 11/$i = a

3rd 007 = printing master 11/$i = b

In all other situations where there is more than one manifestation of the microform, a new record is input rather than repeating the 007 field in one record.  For further information, see Fixed Length Fields - General Information and Appendix M.

Field 007 for microforms is defined in MARC 21 as a fixed-length field consisting of 13 character positions.  In the OCLC system the character positions have been assigned subfield code equivalents.  The field is output to LC from OCLC and distributed by LC as a single subfield $a.

Character positions/subfield codes

00/$a        Category of material

01/$b        Specific material designation

03/$d        Positive/negative aspect

04/$e        Dimensions

05-08/$f     Reduction ratio range/Reduction ratio

09/$g        Color

10/$h        Emulsion on film

11/$i         Generation

12/$j         Base of film


007 ## h $b d $d b $e g $f c--- $g c $h a $i c $j a  {as input on OCLC}

007 ## hdbgc---caca  {as distributed}

[Item is a microform ($a) released as a microfilm reel ($b).  The microform has negative polarity ($d), is 70 mm ($e), has a high reduction ratio ($f), and is in color ($g).  The emulsion is silver halide ($h), it is a service copy ($i), and it is safety base film the type of which cannot be determined ($j).]

Definitions of character positions/subfield codes

00/$a  Category of material

h    Microform

The only GMD appropriate for serials is code "h", microform.  Microform is a generic term for any medium, transparent or opaque, bearing microimages too small to read without magnification.  Microforms include microfilms, microfiches, microopaques, and aperture cards.  Microforms may be reproductions of existing textual or graphic materials or they may be original publications.

01/$b  Specific material designation (SMD)

NOTE:  See MARC 21 Format for Bibliographic Data (01) for definitions of the following codes.

a    Aperture card

b    Microfilm cartridge

c    Microfilm cassette

d    Microfilm reel

e    Microfiche

f     Microfiche cassette

g    Microopaque

z    Other microform type

03/$d  Positive/negative aspect

a    Positive

b    Negative

m   Mixed polarity

u    Unknown

Positive - Code "a" indicates a positive microform in which lines and characters appear dark against a light background.  Microopaques are always coded "a" in this subfield.

Negative - Code "b" indicates a negative microform in which lines and characters appear light against a dark background.

Mixed polarity - Code "m" indicates a microform that is a mixture of positive and negative images.

Unknown - Code "u" indicates a microform of unknown polarity (some colored negatives may appear to be positive if the colors of the original are unknown).

04/$e  Dimensions

For microfilm:

a    8 mm.

d    16 mm.

f     35 mm.

g    70 mm.

h    105 mm.

For microfiche or microopaque:

l    3x5 in. or 8x13 cm.

m   4x6 in. or 11x15 cm.

o    6x9 in. or 16x23 cm.

For aperture cards:

p    3-1/4 x 7-3/8 in. or 9x19 cm.

For any microform:

u    Unknown

z    Other

This byte specifies the dimensions of the microform item, not the dimensions of the image.  For instance, 16 mm. images on 35 mm. microform are coded "f".  Only the most common dimensions are indicated.

Codes "a-h", when applicable, can be used to record the width of the microfilm in millimeters.  Codes "l-o", when applicable, can be used to record the height and width of the microfiche or microopaque in inches or centimeters.  Code "p", when applicable, can be used to record the height and width of an aperture card in inches or centimeters.

05 and 06-08/$f  Reduction ratio range/Reduction ratio

a    Low reduction (less than 16X) (less than 16:1)

b    Normal reduction (for 16X-30X) (16:1-30:1)

c    High reduction (for 31X-60X) (31:1-60:1)

d    Very high reduction (for 61X-90X) (61:1-90:1)

e    Ultra high reduction (for over 90X) (over 90:1)

v    Reduction ratio varies

u    Unknown

The "reduction ratio" is usually given on the target of the microform.  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 for this element.  CONSER catalogers are not required to make these calculations and may use value "u" (unknown) when the reduction ratio cannot be determined.

The reduction ratio is a four-character element.  The first character, "Reduction ratio range" (byte 5), is a code that specifies the ratio range (codes a-u).  The second, third, and fourth characters, "Reduction ratio" (bytes 6-8), identify the specific reduction ratio.

AACR2 requires the reduction ratio range to be recorded when the ratio is ultra high (i.e., over 90X, code "e" in byte 5) or low (i.e., under 16X, code "a" in byte 5).  If the ratio is not ultra high or low, recording the specific ratio is optional.  For preservation microforms, however, given the reduction ratio whenever it is known.  If opting not to give the reduction ratio for other types of microforms, omit subfield $f from the 007 field.  Three fill characters will be supplied for bytes 6-8.

When the reduction ratio range (byte 5) is given, numbers or hyphens must be input in bytes 6-8.  The numeric value is recorded using three digits right justified with leading zeros.  Hyphens are used for any or all digits when unknown.


1.    Reduction ratio range (byte 5) omitted.  No subfield $f given.

007 ## $a h $b d $d b $e g $g c $h a $i c $j a

2.    Reduction ratio range (byte 5) is coded.

$f b---

$f u---

$f e015

$f e03-

$f e1--

For microfilm created by other than the COM (computer-output-microfilm) processes and for microopaque microprints (COM and the like), the "reduction ratio" is actually an "expansion ratio" and refers to the ratio required to produce a legible image.  Most COM is created at 24X-48X "reduction ratios" (codes "b" and "c"), though some COM fiche is at higher ratios (e.g., 72X).  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").

Code "v" (reduction ratio varies) should be used when not all the parts of the microform have the same reduction ratio.  For instance, the contents of two serials may be microfilmed on one piece of film; the type face on the serials may differ, so that one of the serials may be filmed at a 14 to 1 ratio and the other at a 16 to 1 ratio.

LC practice:  LC uses hyphens rather than the numeric range in bytes 6-8.

09/$g  Color

b    Black-and-white

c    Multicolored

m   Mixed

u    Unknown

z    Other

A one-character alphabetic code specifies the color of the image for microforms.  Information provided in this element is used chiefly for archival purposes but should always be provided.

Black-and-white - Code "b" indicates that the microform image is in a single hue, e.g. black-and-white (i.e. black-and-transparent), blue-and-white (i.e. blue-and-transparent), etc.

Multicolored - Code "c" indicates that the microform image is colored, i.e., has more than one color.

Mixed - Code "m" indicates that the microform is a combination of one-color and multicolored images.

10/$h  Emulsion on film

a    Silver halide

b    Diazo

c    Vesicular

m   Mixed emulsion

n    Not applicable

u    Unknown

z    Other

This byte is used chiefly for archival purposes.

A one-character alphabetic code specifies the type of emulsion on film.  The word "emulsion" is used to describe the light-sensitive materials within a microform.  Proper storage and use of microforms requires knowledge of the emulsion they contain.

Silver halide - Code "a" indicates that the emulsion is a compound of silver and halogens.  Silver halide microforms always appear black-and-white (i.e., black-and-transparent).

Diazo - Code "b" indicates a diazo microform.  The 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.

Vesicular - Code "c" indicates a vesicular emulsion.  The 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 permanent 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.

Mixed emulsion - Code "m" indicates the microform has a mixed emulsion.  For instance, a microfilm may have slices of film with one type of emulsion and other slices with another type of emulsion.

Not applicable - Code "n" indicates that the item does not have emulsion on film.  As microopaques are not on film, such items should be coded "n".

11/$i  Generation

a    First generation (master)

b    Printing master

c    Service copy

m   Mixed generation

u    Unknown

This byte is used chiefly for archival purposes.  A one-character alphabetic code specifies the generation aspect.

First generation (master) - Code "a" indicates a first generation.  The first generation is the camera master or COM recorder master.  Code "a" is used for all master films that are made on archival stock in accordance with archival production standards and that are given archival storage under relevant ANSI/NMA standards.

Printing master - Code "b" indicates a printing master which is a microform of any generation employed mainly for the production of other microforms.  Code "b" is used for all masters that are not manufactured, produced, and stored in accordance with archival standards.

Service copy - Code "c" indicates a service copy which is a microform made from another microform that is intended primarily for use rather than for production of other microforms.  These are also referred to as subsequent generations.  Microopaques are always coded "c" in this byte.

Mixed generation - Code "m" indicates a microform copy that is made up of a combination of generations of film.

12/$j  Base of film

n    Not applicable

u    Unknown

z    Other film base

Safety base:

a    Safety base, undetermined

c    Safety base, acetate undetermined

d    Safety base, diacetate

p    Safety base, polyester

r     Safety base, mixed

t     Safety base, triacetate


i     Nitrate base

m   Mixed base (nitrate and safety)

This byte is used chiefly for archival purposes.  A one-character alphabetic code specifies the base of the film.

Not applicable - Code "n" indicates that the item does not have a film base.  Such items are primarily microforms 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".

Unknown - Code "u" indicates that the base of film is unknown.

Other film base - Code "z" indicates a film base for which none of the other defined codes is appropriate.

Safety base, undetermined - Code "a" indicates a safety base film whose type cannot be determined.

Safety base, acetate undetermined - Code "c" indicates an acetate safety base film whose exact type cannot be determined, i.e., where it is unknown if the type is diacetate or triacetate.

Safety base, diacetate - Code "d" indicates a cellulose diacetate film base.  Introduced before World War I for home movies, diacetate 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.

Safety base, polyester - Code "p" indicates a film base made of synthetic resin (e.g., estar).  During the 1980s, it became the most widely used base for microfilming of source documents.

Safety base, mixed - Code "r" indicates that there are mixed safety base films spliced together, but no nitrate film.

Safety base, triacetate - Code "t" indicates a 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.

Nitrate base - Code "i" indicates a cellulose nitrate film base.  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.

Mixed base (nitrate and safety) - Code "m" indicates a combination of nitrate base and safety base film.  The use of mixed bases, spliced together, can be found in microforms from the early 1950s.

Related fields, etc.

Fixed Fields- -General Information, 008/22, 008/23, 533, Appendix M

CCM Module 32

007 Physical Description Fixed Field - Microform  (MARC 21 Format for Bibliographic Data)

See also:

007  Physical Description Fixed Fields

Section E.  MARC 21 Format for Serials as Applied Within CONSER

CONSER Editing Guide:  Contents