Tracings and References-General Information
MARC 21 Classification - Concise
2008
This is an ARCHIVED VERSION of the
2008 electronic edition of the MARC 21 Concise
Formats. Please see loc.gov/marc/concise/
for the most up-to-date version of the electronic MARC 21
Concise Formats.
Introduction
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:
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).
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).
Simple 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
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
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 subfields
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
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. Classification number in
the tracing field is 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. Field 685 (History Note) may be included in the
record to give additional information about the history of
the classification number contained in the tracing.
b - New classification number. 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:
in a cross reference display. If the meaning of the number in
field 153 is changed only for certain subjects, this
complex information is conveyed in field 685 (History Note).
This type of reference might be used by a library that
assigns new classification numbers to new books but does not
reclassify existing ones when a new edition is published.
i - Reference instruction phrase in subfield $i Used in
conjunction with subfield $i (Reference instruction phrase)
when explicit text is needed that does not fall into any
other category.
j - See reference .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. 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. 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. 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. 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
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. 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. 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. 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
One-character alphabetic code that enables the generation or
suppression of a cross reference from a 453 or 553 field.
a - Reference not displayed. 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. 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
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
n - Not applicable
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 $i (Explanatory text) contains
textual information in field 253 (Complex See Reference) or
field 353 (Complex See Also Reference).
Examples
|
|
|
|
|
|
|
|
|
|
| 553 |
0#$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 |
|
|
|
|
|
|
|
|
|
|
| 453 |
0#$wahna$a332.454$hSocial sciences$hEconomics$hFinancial
economics$hMoney$hForeign exchange$jForeign exchange with
a paper standard |
|
|
|
|
|
|
|
|
|
|
| 553 |
0#$wbnna$a787.2$hThe arts. Fine and decorative
arts$hMusic$kInstruments and their music$kSpecific
instruments and their music$hStringed instruments
(Chordophones). Bowed string instruments$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$hPrime movers and heat engineering$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$tsociology
of working class |
|
|
|
|
|
|
|
|
|
|
| 553 |
0#$wl$a331$hSocial sciences$hEconomics$kEconomics of
labor, finance, land, energy$jLabor economics$tsociology
of labor |
|
|
|
|
|
|
|
|
|
|
| 553 |
0#$wmh$a331.011$hSocial sciences$hEconomics$kEconomics of
labor, finance, land, energy$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$jPumps. Pneumatic
pumps$thydraulic 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[The 553 field
contains a tracing from a DDC centered entry, or broader
number span, which facilitates online browsing.] |
|
|
|
|
|
|
|
|
|
|
| 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 |
|
|
|
|
|
|
|
|
|
|
| 253 |
0#$iFor rules
of practice before a separately classed agency, see the
issuing agency |
The Library of Congress
>> Librarians,
Archivists >> Standards >>
MARC