045 Subfield $a - Time Period Code (045 Time Period of Content )

Subfield $a contains a four-character alphanumeric code derived from the following Time Period Code Table for B.C. and C.E. time periods. Each time period code associated with a heading is contained in a separate subfield $a.

Explanations and Examples of B.C. and C.E. dates follow the table.

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.

Examples:

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.

Examples:

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-

To return, select:

045 Time Period of Content