MARC 21 Concise Classification: Tracings and References--General Information

This is an ARCHIVED VERSION of the 2000 electronic edition of the MARC 21 Concise Formats. Please see www.loc.gov/marc/concise/ for the most up-to-date version of the electronic MARC 21 Concise Formats.

INTRODUCTION
TRACING FIELDS
REFERENCE NOTE FIELDS
SIMPLE CROSS REFERENCE FIELDS
COMPLEX CROSS REFERENCE FIELDS

INTRODUCTIONf

A cross reference is used to refer between classification numbers that are constructed according to the classification scheme that is identified in field 084 (Classification Scheme and Edition). It leads from an invalid classification number to a valid classification number or from one valid classification number to another valid classification number. Tracings or reference note fields are used to direct the user to another classification number, often for specific aspects of a topic. Cross reference displays may be generated by combining the contents of a tracing or a reference note field and field 153 (Classification Number) of a record. In some cases the inputting library may provide both a tracing and a reference note field and choose to suppress the tracing for display purposes.
In the MARC 21 classification format, tracing and reference fields are defined to allow the generation of simple and complex references. These data elements are divided into the following groups where descriptions of specific fields can be found:

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TRACING FIELDS

Tracing fields lead directly from one number to another number. A 453 Invalid Number Tracing field leads from an invalid number to a valid number. A 553 Valid Number Tracing field leads from one valid classification number to another, often for classification of certain topics. Cross reference displays generated from the tracing fields are called simple cross references. In a simple cross reference display, the content of the 453 or 553 field is the number referred from, and, following a reference instruction phrase, the content of the 153 field is the number referred to. In the tracing fields, the reference instruction phrase is associated with a code in subfield $w/0 (Special relationship) and/or subfield $w/1 (Hierarchical relationship). In unusual cases, the reference instruction phrase may be carried explicitly in subfield $i (Reference instruction phrase).

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REFERENCE NOTE FIELDS

Reference note fields lead from one classification number to one or more other classification numbers. A reference note field is used when more complex reference instruction is needed than can be conveyed by one or more simple cross references generated from 453 and/or 553 tracing fields. There are two types of reference note fields: 1) see references (field 253), which refer to a classification number in another record and 2) see also references, which guide the user to related topics in other valid classification numbers (field 353).
Cross reference displays constructed from the reference note fields are complex cross references. In a complex cross reference display, the content of the 153 field of a record is the number referred from, and, following a reference instruction phrase, the reference note field contains the number(s) referred to. In the reference note fields, the reference instruction is given as explicit text in subfield $i (Explanatory text).

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SIMPLE CROSS REFERENCE FIELDS

Simple cross references are generated for display from tracing fields. Displays may vary from one system to the next; those shown below are only suggestions. The content of subfield $i and subfield $w determine the reference instruction phrase used with the tracing. The character positions defined for subfield $w are described here. Subfield $t (Topic) provides additional information about the use of the classification number.

Subfield $i - Reference instruction phrase

Contains a special reference instruction phrase that may be used in a cross reference display when the generation of a reference instruction phrase based on a code in control subfield $w/0 is not possible. When a tracing field contains subfield $i, subfield $w/0 contains code i (Reference instruction phrase in subfield $i).

Subfield $t - Topic

Specifies the topics for which the tracing is appropriate. If the topic is the same as the caption in field 153 (Classification Number), subfield $j (Caption), the topic need not be repeated in subfield $t. However, if the topic is the same as the caption of the number referred to in subfield $j of field 453 or 553, the topic is still contained in subfield $t to facilitate a display of the tracing.

Subfield $w - Control subfield

Four fixed-position character positions (designated as $w/0, $w/1, $w/2, and $w/3) that indicate whether special instructions apply to the display of the 453 or 553 classification number, whether the reference should be displayed, and whether a field 685 (History Note) is associated with the tracing. Because the definitions of the codes in subfield $w are dependent on the character position in which they occur, the coding of any character position mandates that each preceding character position contains a code or fill character ( | ); succeeding character positions need not be used. For example, if subfield $w/1 (Hierarchical relationship) is not applicable, but $w/3 (History reference) is, subfield $w/1 must contain code n (Not applicable), and subfield $w/2 must contain either a code or a fill character. If $w/1, $w/2, and $w/3 are not applicable, only $w/0 need be coded.

$w/0 - Special relationship

Subfield $w/0 contains a one-character alphabetic code that describes a relationship between the classification numbers contained in field 153 and fields 453 or 553. The codes may be used to generate a special reference instruction phrase in a cross reference display. If more than one code is applicable, the field may be repeated and the generation of a display of one of the tracings may be suppressed by code a (Reference not displayed) in subfield $w/2 (Reference display).

a - Previous classification number
A number previously used for the subject. It directs the user to the currently used number in field 153 (Classification Number). The code may be used to generate a special reference instruction phrase such as see also under the new number: in a cross reference display.
b - New classification number
Indicates that the number in the tracing field entirely supersedes the number contained in field 153. The code may be used to generate a special reference instruction phrase such as see also under the previous number:.
i - Reference instruction phrase in $i
Code i is used in conjunction with subfield $i (Reference instruction phrase). Guidelines for applying code i are given under the description of subfield $i.
j - See reference
Indicates that the number in the tracing field is a simple see reference that guides the user from the number(s) in the tracing field (field 453 or 553) to the number(s) in field 153 (Classification Number). The code may be used to generate a special reference instruction phrase such as see or For [topic] see [number].
k - Class elsewhere reference
Indicates that the topic in subfield $t (Topic) of the tracing field is classed in another number that is not a subdivision of the number in subfield $a (Classification number element--Single number or beginning number of span) of field 553. The code may be used to generate a special instruction phrase such as Class [topic] in [number].
l - See also reference
Indicates that the number in the tracing field guides the user from the number(s) in field 553 to related topics classed in the number(s) in field 153. The code may be used to generate a special instruction phrase such as Cf. [number] [topic] or see also [number] for [topic].
m - Standard subdivisions do-not-use reference
Indicates that one or more standard subdivisions may not be used with the number in the tracing field. The code may be used to generate a special instruction phrase such as Do not use for [topic]; class in [number].
n - Not applicable
Indicates that the relationship between the heading in the tracing field and the 153 heading is not one of the special relationships for which other codes are defined in subfield $w/0. A tag related reference instruction phrase such as see or see also may be used in a cross reference display from the related heading. If code n is applicable, subfield $w need not be coded unless a subsequent character position is required.

$w/1 - Hierarchical relationship

A one-character alphabetic code which indicates the nature of the hierarchy when the tracing is for a hierarchical relationship between topics. The codes may be used to generate a special instruction phrase in a cross reference display.

g - Number representing broader topic
Indicates that the number in the tracing field represents a broader topic than the number at the preceding level of the caption hierarchy that is contained in field 153 (Classification Number). The code may be used to generate a special reference instruction phrase such as see also under the narrower number: in a cross reference display.
h - Number representing narrower topic
Indicates that the number in the tracing field represents a narrower topic than the number at the lower level of the caption hierarchy that is contained in field 153. The code may be used to generate a special reference instruction phrase such as see also under the broader number: in a cross reference display.
n - Not applicable
Indicates that a hierarchical relationship is not applicable to the tracing. If code n is applicable, subfield $w/1 need not be coded unless a subsequent character position is required.

$w/2 - Reference display

Subfield $w/2 contains a one-character alphabetic code that enables the generation or suppression of a cross reference from a 453 or 553 field.

a - Reference not displayed
Indicates that the generation of a cross reference display from a tracing field should be suppressed. Code a is used when a 253 or 353 complex reference field contains the reference to be displayed or when it is otherwise not desirable to display the reference.
n - Not applicable
Indicates that there is no reference display restriction on the tracing field. If code n is applicable, subfield $w/2 need not be coded unless $w/3 is used.

$w/3 - History reference

A one-character alphabetic code that indicates whether field 685 (History Note) in a record refers to the number in a 453 or 553 tracing.

a - History reference, field 685 used
Indicates that the record contains a field 685 that contains further information about the number in the 453 or 553 tracing field.
b - Not applicable
Indicates either that the record does not contain field 685 (History Note) or that field 685 refers to the classification number contained in field 153. If code n is applicable, subfield $w/3 need not be coded.

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COMPLEX CROSS REFERENCE FIELDS

Complex cross references are carried directly in records as reference note fields. They are used when relationships exist between classification numbers that cannot be adequately conveyed by one or more simple cross references generated from 453 or 553 tracings. Subfield $i (Explanatory text) contains textual information in field 253 (Complex See Reference) or field 353 (Complex See Also Reference).

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EXAMPLES

453	0#$wj $aH61.5 $hSocial Science (General) $hTheory. Method. Relation to other subjects $jStatistical methods
253	2#$iFor metabolism within a specific function, system, or organ, see the function, system, or organ, e.g., metabolism of plasma $a612.116
553	0#$wl $aNK5030 $cNK5035 $hDecorative arts. Applied arts. Decoration and ornament $hOther arts and art industries $jFairground art $tHandicraft of carousel horses
553	0#$wk $a541.24 $hNatural sciences and mathematics $hChemistry and allied sciences $kChemistry $kGeneral topics in chemistry $hPhysical and theoretical chemistry $hTheoretical chemistry $jAtomic structure $tperiodic table
253	0#$iFor rules of practice before a separately classed agency, see the issuing agency
453	0#$wahna $a133.3239 $hPhilosophy, paranormal phenomena, psychology $hParanormal phenomena $hParapsychology and occultism $hDivinatory arts $hFortune-telling by crystals and stones; dowsing; fortune-telling by cards, tea leaves and coffee grounds, oracles and sibyls $hDowsing $jTelediesthesia (Distant prospection)
553	0#$wbnna $a787.2 $hThe arts. Fine and decorative arts $hMusic $kInstruments and their music $kSpecific instruments and their music $hStringed instruments (Chordophones). Bowed stringed instruments $jViolins
553	1#$wj $zP-PZ1 $a691 $hTable for languages $hLexicography $hDictionaries $hOther special lists $jWord frequency lists $tResearch on word frequency, etc., in connection with machine translating
553	0#$wjg $a621.42 $hTechnology (Applied sciences) $hEngineering and allied operations $hApplied physics $hHeat engineering and prime movers $jStirling engines and air motors
553	0#$wk $a331.2162 $hSocial sciences $hEconomics $kEconomics of labor, finance, land, energy $hLabor economics $hConditions of employment $hCompensation $hMethods of compensation $tTime payments
553	0#$wl $a331 $hSocial sciences $hEconomics $kEconomics of labor, finance, land, energy $jLabor economics $tsociology of labor
553	0#$wl $a331 $hSocial sciences $hEconomics $hEconomics $kEconomics of labor, finance, land, energy $jLabor economics $tsociology of labor
553	0#$wmh $a331.011 $hSocial sciences $kEconomics of labor, finance, land, energy $hLabor economics $hPhilosophy and theory $jRights and position of labor $tsystems analysis applied to labor economics
553	0#$wjg $a621.69 $hTechnology (Applied sciences) $hEngineering and allied operations $hApplied physics $hBlowers, fans, pumps $kPumps $jPumps. Pneumatic pumps $thand pumps
553	0#$wjg $a621.69 $hTechnology (Applied sciences) $hEngineering and allied operations $hApplied physics $hBlowers, fans, pumps $kPumps $jPumps. Pneumatic pumps $treciprocating pumps
553	0#$wjg $a621.69 $hTechnology (Applied sciences) $hEngineering and allied operations $hApplied physics $hBlowers, fans, pumps $kPumps $jPumps. Pneumatic pumps $trotary pumps
553	0#$wjg $a621.69 $hTechnology (Applied sciences) $hEngineering and allied operations $hApplied physics $hBlowers, fans, pumps $kPumps $jPumps. Pneumatic pumps $tcentrifugal pumps
553	0#$wkh $a666.5 $c666.6 $hTechnology (Applied sciences) $hChemical engineering and related technologies $hCeramic and allied technologies $jSpecific types of pottery $tcomprehensive works
553	0#$wnga $a230 $c280 $hReligion $jChristianity
453	1#$wanna $z2 $a71335 $hGeographic Areas, Historical Periods, Persons $kSpecific continents, countries, localities; extraterrestrial worlds $kThe modern world; extraterrestrial worlds $hNorth America $hCanada $hOntario $kSouthern Ontario $hLake Erie region $jSt. Thomas

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