| First Indicator | Second Indicator |
|---|---|
| Existence in NAL collection # - No information provided 0 - Item is in NAL 1 - Item is not in NAL |
Undefined # - Undefined |
| Subfield Codes | |
|---|---|
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Classification or call number that is assigned by the National Agricultural Library (NAL).
May also contain NAL accession numbers for visual materials.
Prior to 1965, NAL used a USDA library classification scheme. In 1965, NAL began using the Library of Congress Classification for all newly-cataloged materials. Serial-like items have retained the old call number whenever possible; thus, both schemes are still in use. NAL also assigns sequential accession numbers to dissertations and abstracts.
Prefixes may occur in NAL call numbers. "A" specifies a USDA publication in the old USDA scheme; "a" specifies a USDA publication in the LC classification scheme; "R" specifies a rare book; "J" specifies a juvenile book; and "Fo" specifies a folio publication.
First Indicator - Existence in NAL collection
Whether or not the item is contained in the NAL collection.
Used for all call numbers assigned by institutions other than NAL.
| 070 | ##$aSB945.A5 | ||||||||
| 245 | 00$aAphids as crop pests/$cedited by Helmut F. van Emden and Richard Harrington. | ||||||||
Second Indicator - Undefined
Undefined and contains a blank (#).
$a - Classification number
Classification number portion of the NAL call number. Subfield $a is repeated to record alternative classification numbers.
| 070 | 0#$aHD3492.H8$bL3 | ||||||||
| 070 | 0#$aTRANSL$b17828 [Number assigned to a translation.] |
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$b - Item number
NAL item number.
| 070 | 0#$a281.9$bC81A [Number assigned from the USDA library scheme.] |
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| 070 | 0#$aQH301.A5 $b1981 [Number assigned from the LC classification scheme.] |
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$0 - Authority record control number or standard number
See description of this subfield in Appendix A: Control Subfields.
$1 - Real World Object URI
See description of this subfield in Appendix A: Control Subfields.
$8 - Field link and sequence number
See description of this subfield in Appendix A: Control Subfields.
Punctuation - Field 070 does not end in a period unless the field ends in an abbreviation, initial/letter, or other data that ends in a period.
Capitalization - Alphabetic characters in the classification portion of the field are usually uppercase.
In the serials specifications, the use of the second indicator position to indicate the type of series was made obsolete in 1976. The values were: 0 (No series involved), 1 (Main series), 2 (Subseries), 3 (Sub-subseries).