DATE: December 10, 2004
REVISED:
NAME: Definition of Field 766 in the MARC 21 Classification Format
SOURCE: Library of Congress
SUMMARY: This paper proposes the definition of a field 766 for Secondary Table Information. The field would be used to indicate whether a secondary table is applied in breaking down the number or span of numbers contained in the 153 $a or 153 $a-c of a classification table record, and if so to characterize the entity in the 153 $j so that the appropriate secondary table can be selected.
KEYWORDS: Field 766 (CD); Secondary table information (CD)
STATUS/COMMENTS:
12/10/04 - Made available to the MARC 21 community for discussion.
01/15/05 - Results of the MARC Advisory Committee discussion - Approved
03/02/05 - Results of LC/LAC/BL review - Approved. The field is repeatable (this was inadvertently left out of the proposal).
Some Library of Congress Classification (LCC) schedules provide a range of numbers for a topic and employ an external table to break down the range by specific places such as regions or countries. Individual regions or countries in this primary table may in turn be subarranged by a secondary table. The primary table often includes a mix of some numbers or spans that are subarranged by a secondary table and some that are not.
For example, the range HB2171-2368 is provided for "Urban population. By region or country." The span of numbers is broken down by Table H2, which lists the individual regions and countries of the world. Each individual region or country is further subarranged by one of three secondary tables, according to whether it is a 2-number country, a 1-number country, or a 1-number region. No secondary table is applied for the United States. Instead, a more detailed breakdown for the United States is provided in Table H2 itself, and that breakdown is used in lieu of a secondary table.
The MARC 21 Classification Format does not currently provide a machine-readable method of specifying whether or not an individual number or span of numbers in a primary table uses a secondary table. Therefore, an online Library of Congress Classification system such as Classification Web cannot distinguish between those numbers or spans in a primary table that are subarranged by a secondary table and those that are not. By default links are provided to secondary tables from all numbers within a primary table, even those that are not intended to use the secondary table. This is unfortunate given that the system is able to automatically calculate specific classification numbers by applying tables programmatically. The user must be independently aware of the fact that the secondary table is applied to some of the numbers in the primary table, but not to others, as the system will calculate invalid numbers if the user selects the secondary table link for a caption to which the secondary table is not intended to be applied.
Furthermore, the format does not currently provide a way to characterize the individual entities available when applying the primary table. Currently, in cases where a secondary table is applicable, a system such as Classification Web is able only to offer the user a menu of possible secondary tables to choose from, not the specific numbers that are a result of the application. Thus the system is not able to link automatically to the appropriate secondary table without user intervention. The user must be independently aware of which numbers to use, and which numbers not to use in the secondary table, as the system will calculate invalid numbers if the user selects the secondary table link for a caption to which the secondary table is not intended to be applied. The current situation may result in inefficiency, or at times even inaccuracy, in determining the correct classification.
Field 766 would serve to identify those classification records where a secondary table applies and those where the secondary table does not apply. It would also provide a method of characterizing the entities in 153 $j subfields in the primary table so that a system can automatically link to the appropriate secondary table without first forcing the user to select from a menu. This would be done by matching the data in field 763 (Internal Subarrangement or Add Table Entry) of the classification record with the data in a new field 766, so that the correct subarrangement will be automatically supplied to the user.
The new field would need to be added to all records within spans that have a secondary table subarrangement. This could be done almost completely by program.
Field 766 would be called "Secondary Table Information" and would have the following indicators and subfield codes:
| Field 766 (Secondary Table Information) | |||||
| First indicator | |||||
| # Undefined | |||||
| Second indicator | |||||
| # Undefined | |||||
| Subfield codes | |||||
| $a Secondary table applicability (NR) | |||||
| $y Type of division (R) | |||||
| $6 Linkage (NR) | |||||
| $8 Field link and sequence number (R) | |||||
Subfield $a would contain a code (e.g., a for applicable; n for not applicable) indicating whether or not a secondary table is applicable for breaking down the number or span of numbers in field 153. Subfield $y would contain text that identifies the type of division to which the entity in the 153 $j belongs. The text would match that of the corresponding $y subfield in the 763 field in the schedule record with which the secondary table is used.
| Example 1: | ||||||
| Schedule record: | ||||||
| 153 | ## | $aHD6091 $cHD6220.9 $hIndustries. Land use. Labor $hLabor. Work. Working class $hClasses of labor $hWomen $jBy region or country | ||||
| 762 | $zH5 | |||||
| 763 | 08 | $81.1 | ||||
| 763 | 08 | $81.2 $zHD6091/1 $y4 number countries | ||||
| 763 | 10 | $81.3 $zHD6091/2 $y1 number countries | ||||
| 763 | 10 | $81.4 $zHD6091/3 $y1 number regions | ||||
| Table record: | ||||||
| (This record for Argentina has a 4 number span that may be applied.) | ||||||
| 153 | ## | $z5 $a27 $c30 $hTables of geographical divisions $hLatin America $hSouth America $jArgentina | ||||
| 766 | ## | $aa $y4 number countries | ||||
| Example 2: | ||||||
| Schedule record: | ||||||
| 153 | ## | $aHB2171 $cHB2368 $hEconomic theory. Demography $hDemography. Population. Vital events $hPopulation geography. Migration $hUrban population $jBy region or country | ||||
| 762 | $zH2 | |||||
| 763 | 08 | $zHB2171/1 $y2 number countries | ||||
| 763 | 08 | $zHB2171/2 $y1 number countries | ||||
| 763 | 10 | $zHB2171/3 $y1 number regions | ||||
| Table record: | ||||||
| (In this case a table is applicable for most numbers in the span under "By region or country" (above), but not those for the United States, since they are explicitly encoded in separate records.) | ||||||
| 153 | ## | $zH2 $a11 $hTables of geographical divisions $hNorth America $hUnited States $jSouthern States | ||||
| 766 | ## | $an | ||||
Define field 766 (Secondary Table Information) in the MARC 21 Classification Format.
| Field 766 (Secondary Table Information) | |||||
| First indicator | |||||
| # Undefined | |||||
| Second indicator | |||||
| # Undefined | |||||
| Subfield codes | |||||
| $a Secondary table applicability (NR) | |||||
| $y Type of division (R) | |||||
| $6 Linkage (NR) | |||||
| $8 Field link and sequence number (R) | |||||
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