045  Time Period of Content (NR)

The four-character time period code. The first two characters represent the earliest period covered. The last two represent the latest period covered. If a single two-character code encompasses the entire period, enter the code twice. Use the codes from the table below:

• B.C. (Before Common Era) dates. Use a lowercase alphabetic character to represent the millennium and a digit to represent the century. If the century is not known, enter a hyphen instead of a digit.

  045			a-c-
  650		0	Bronze age
  [3000–100 B.C.]

  045			c4c6
  651		0	Egypt ǂx History ǂy Eighteenth dynasty, ca. 1570-1320 B.C.

  045			d7d9
  651		0	Rome ǂx History ǂy Republic, 265-30 B.C.

• C.E. (Common Era) dates. Use a lowercase alphabetic character to represent the century and a digit to represent the decade. If the decade is not known, enter a hyphen instead of a digit. If more than one time period code applies, enter each in a separate subfield ǂa.

  045			x8x8
  650		0	Bhopal Union Carbide Plant Disaster, Bhopal, India, 1984

  045			t-v-
  650		0	Catalan literature ǂy 16th-18th centuries

  045			x-x-
  650		0	Civilization, Modern ǂy 20th century

  045			y-y-
  650		0	Twenty-first century ǂx Forecasts

  045			o6s8
  651		0	Great Britain ǂx History ǂy Medieval period, 1066-1485

  045			d8h2
  651		0	Greece ǂx History ǂy 146 B.C.-323 A.D.

A specific time period formatted as yyyymmddhh preceded by code c for B.C. or code d for C.E. The era and year are required. The month, day, and hour (based on the 24-hour clock) are optional.

Enter only known elements with a five-character minimum. Use subfield ǂa if you cannot determine the first five characters.

Enter each 9999 B.C. through C.E. time period associated with the heading in a separate subfield ǂb.

A formatted time period consisting of as many numeric characters as are needed to represent the number of years B.C. Enter each pre-9999 B.C. time period associated with the heading in a separate subfield.

Data that link fields when non-Latin script is entered. This subfield is system supplied and does not appear in OCLC online displays. Do not manually add subfield ǂ6. For more information about subfield ǂ6, see Control Subfields.

For information about subfield ǂ8, see Control Subfields.