007/12 Microform (/00 = h) |
Base of film (Variable Control Field - Physical Description Fixed Field) |
Character position definition and scope:
A one-character alphabetic code indicates the 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 fill character ( | ) is used when no attempt has been made to code this position.
Record requirements for National-level and Minimal-level records: Optional.
Guidelines for applying content designators:
Codes: |
Descriptions: |
Safety base: |
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a |
Safety base, undetermined Safety base film whose type has not been identified. |
c |
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d |
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p |
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r |
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t |
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Nitrate: |
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i |
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m |
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All other: |
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n |
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u |
Unknown The base of film of the microform cannot be determined. |
z |
Other A film base for which none of the other defined codes is appropriate. |
| |
No attempt to code |
b - Not safety base [obsolete]: Code b was made obsolete in 1991 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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