Library of Congress >> MARC >> Bibliographic >> 01X-09X >> 045

045 - Time Period of Content (NR)


MARC 21 Bibliographic - Full
October 2003

First Indicator
Type of time period in subfield $b or $c
# - Subfield $b or $c not present
0 - Single date/time
1 - Multiple single dates/times
2 - Range of dates/times

Second Indicator
Undefined
# - Undefined


Subfield Codes
$a - Time period code (R)
$b - Formatted 9999 B.C. through C.E. time period (R)
$c - Formatted pre-9999 B.C. time period (R)
$6 - Linkage (NR)
$8 - Field link and sequence number (R)

FIELD DEFINITION AND SCOPE

Time period code (subfield $a) and/or a formatted time period (subfield $b and/or $c) associated with an item.

Time period code in subfield $a is derived from the B.C. (Before Common Era) and/or C.E. (Common Era) lists in the Time Period Code Table provided under the description of subfield $a.

For books and continuing resources, this field indicates the period depicted by the content of the item (e.g., history of the 16th century would be coded as 045 ##$at-t- or 045 2#$bd1500$bd1599).

For collections of mixed materials, this field indicates the time period covered by the collection.

For computer files, this field indicates the period covered by the data in the file (e.g., a data file containing statistics for the period 1950-1960 would be coded 045 ##$ax5x6).

For cartographic material, this field indicates the date portrayed on the item, that is, the situation date. A currently prepared map of Rome in 50 B.C. would be coded for the B.C. date. A remote-sensing map which depicts the time the satellite recorded the image would be coded for that time.

For printed music and sound recordings, this field indicates the period of the composition, and will usually relate to the date of the composition. If the precise date of composition cannot be determined, an approximate date (or range of dates) or the dates of the composer are used.

For motion pictures and videorecordings, this field indicates the time period depicted in the film (e.g., a videorecording documentary of the history of the brewing industry in Wisconsin for the period 1900-1986 would be coded 045 2#$bd1900$bd1986).

For two-dimensional nonprojectable graphic representations, this field indicates the time period depicted in the graphic (e.g., a collection of photographs from 1870 to 1930 would be coded 045 ##$aw7x3).

For artifacts, this field indicates the time period covered by the content of the artifact (e.g., a model of an automobile repair shop of the 1920-1930 period would be coded 045 ##$ax2x3).

For naturally occurring objects, this field indicates the time period of the content, that is, the time period that the item originated (e.g., a geode would be coded for the time period when it was formed).


GUIDELINES FOR APPLYING CONTENT DESIGNATORS

INDICATORS

First Indicator - Type of time period in subfield $b or $c
Whether a subfield $b or $c is present in the field and, when subfield $b or $c is present, the type of time period it contains. The values distinguish among a single date/time, multiple single dates/times, and a range of dates/times.
# - Subfield $b or $c not present
Neither subfield $b or $c is present.
651 #0$aEgypt$xEconomic conditions$yTo 332 B.C.
045 ##$aa0d6
0 - Single date/time
Subfield $b and/or $c is present and contains a single date/time.
650 #0$aLunar petrology.
045 0#$c2500000000
1 - Multiple single dates/times
Multiple $b and/or $c subfields are present, each containing a date/time.A range of dates/times is identified by value 2.
045 1#$bd1972$bd1975
[1972 and 1975]
2 - Range of dates/times
Two $b and/or $c subfields are present and contain a range of dates/times.Multiple single dates and/or times are identified by value 1 (Multiple single dates/times).
650 #0$aShenandoah Valley Campaign, 1864 (May-August)
045 2#$bd186405$bd186408
650 #0$aAurignacian culture.
045 2#$c25000$c15000
Second Indicator - Undefined
Undefined and contains a blank (#).

SUBFIELD CODES

$a - Time period code
Four-character alphanumeric code derived from the "Time Period Code Table" for B.C. and A.D. time periods.
Table is found in MARC 21 Format for Bibliographic Data under the description of field 045.
Each time period code associated with a heading is contained in a separate subfield $a.
Time Period Code Table
B.C. (Before Common Era)
(Add 0, 1, 2, ... 9 to each alphabetic character for the decade)
Code Time period
a0 before 2999
b0 2999-2900
b1 2899-2800
b2 2799-2700
b3 2699-2600
b4 2599-2500
b5 2499-2400
b6 2399-2300
b7 2299-2200
b8 2199-2100
b9 2099-2000
c0 1999-1900
c1 1899-1800
c2 1799-1700
c3 1699-1600
c4 1599-1500
c5 1499-1400
c6 1399-1300
c7 1299-1200
c8 1199-1100
c9 1099-1000
d0 999-900
d1 899-800
d2 799-700
d3 699-600
d4 599-500
d5 499-400
d6 399-300
d7 299-200
d8 199-100
d9 99-1
C.E. (Common Era)
Code Time period
e 1-99
f 100-199
g 200-299
h 300-399
i 400-499
j 500-599
k 600-699
l 700-799
m 800-899
n 900-999
o 1000-1099
p 1100-1199
q 1200-1299
r 1300-1399
s 1400-1499
t 1500-1599
u 1600-1699
v 1700-1799
w 1800-1899
x 1900-1999
y 2000-2099
For B.C. dates, the lowercase alphabetic character represents the millennium and the digit represents the century. If the century is not known, a hyphen (-) is used instead of a number. A single century or a period within a century is coded by repeating the appropriate two-character code to create the required four-characters.
651 #0$aRome$xHistory$yRepublic, 265-30 B.C.
045 ##$ad7d9
650 #0$aBronze age.
045 ##$aa-c-
[3000-1000 B.C.]
651 #0$aEgypt$xHistory$yEighteenth dynasty, ca. 1570-1320 B.C.
045 ##$ac4c6
For C.E. dates, the lowercase alphabetic character represents the century. A digit (0-9) is added to represent the decade. If the decade is not known, a hyphen (-) is used instead of a number.
A single year or a period within a decade is coded by repeating the appropriate two-character code to create the required four characters.
651 #0$aGreat Britain$xHistory$yMedieval period, 1066-1485.
045 ##$ao6s8
650 #0$aBhopal Union Carbide Plant Disaster, Bhopal, India, 1984.
045 ##$ax8x8
650 #0$aCivilization, Modern$y20th century.
045 ##$ax-x-
650 #0$aCatalan literature$y16th-18th centuries.
045 ##$at-v-
651 #0$aGreece$xHistory$y146 B.C.-323 A.D.
045 ##$ad8h2
650 #0$aTwenty-first century$xForecasts.
045 ##$ay-y-
$b - Formatted 9999 B.C. through C.E. time period
Specific time period recorded in the pattern yyyymmddhh and preceded by a code for the era (c for B.C.; d for C.E.).
Era and year are required components; month, day, and hour are optional.
First indicator position values 0-2 specify whether the time period in subfield $b is a single date, multiple dates, or a range of dates. Each 9999 B.C. through C.E. time period associated with the heading is contained in a separate subfield $b.
651 #0$aFrance$xHistory$yRevolution, 1791-1797.
045 2#$bd1791$bd1797
651 #0$aJapan$xHistory$yFebruary Incident, 1936 (February 26)
045 0#$bd19360226
651 #0$aChina$xHistory$y221 B.C.-960 A.D.
045 2#$ad7n6$bc0221$bd0960
$c - Formatted pre-9999 B.C. time period
Formatted time period that consists of as many numeric characters as are needed to represent the number of pre-9999 years B.C.
First indicator position values 0-2 specify whether the time period in subfield $c is a single date, multiple dates, or a range of dates. Each pre-9999 B.C. time period associated with the heading is contained in a separate subfield $c.
650 #0$aGeology, Stratigraphic$yMesozoic.
045 2#$c225000000$c70000000
$6 - Linkage
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.

INPUT CONVENTIONS

Punctuation - No marks of punctuation are used in field 045.
Order of subfields - Subfield $c (Formatted pre-9999 B.C. time period) is input preceding subfield $b (Formatted 9999 B.C. through C.E. time period).

CONTENT DESIGNATOR HISTORY

Indicator 1 - Type of time period in subfield $b or $c [NEW, 1979]

$b - Chronological date/time [NEW, 1979]
$b - 9999 B.C. through C.E. time period, formatted [REDEFINED, 1987]
$c - Pre-9999 B.C. time period, formatted [NEW, 1987]
Subfield $b was redefined for 9999 B.C. through C.E. time periods when subfield $c was defined for pre-9999 B.C. time periods in 1987. Prior to that time, all dates/times were contained in subfield $b.

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