Type of time period in subfield $b or $c
# - Subfield $b or $c not present
0 - Single date/time
1 - Multiple single dates/times
2 - Range of dates/times
# - Undefined
|$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)
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 ##$ax2x3).
For naturally occurring objects, this field indicates the time period of the content, that is, the time period that the item originated (e.g., a geode would be coded for the time period when it was formed).
|651||#0$aEgypt$xEconomic conditions$yTo 332 B.C.|
[1972 and 1975]
|650||#0$aShenandoah Valley Campaign, 1864 (May-August)|
|651||#0$aRome$xHistory$yRepublic, 265-30 B.C.|
|651||#0$aEgypt$xHistory$yEighteenth dynasty, ca. 1570-1320 B.C.|
|651||#0$aGreat Britain$xHistory$yMedieval period, 1066-1485.|
|650||#0$aBhopal Union Carbide Plant Disaster, Bhopal, India, 1984.|
|650||#0$aCivilization, Modern$y20th century.|
|650||#0$aCatalan literature$y16th-18th centuries.|
|651||#0$aGreece$xHistory$y146 B.C.-323 A.D.|
|651||#0$aJapan$xHistory$yFebruary Incident, 1936 (February 26)|
|651||#0$aChina$xHistory$y221 B.C.-960 A.D.|