APPENDIX E: Time Period Code

The purpose of the Time Period Code is to allow access to a range of materials covering a particular era or related to a particular date. In UNIMARC, the code is entered in field 661. The code was developed at the U.S. Library of Congress for use in the USMARC format and was originally called the Chronological Coverage Code.

Code List

The Time Period Code consists of four alphanumeric characters assigned according to the tables given below. For B.C. dates, a lowercase alphabetic character represents the millennium and a digit represents the century. If the century is not known, a hyphen '-' is used instead of a number. For A.D. dates, a lowercase alphabetic character represents the century and a digit represents the decade. If the decade is not known, a hyphen is used instead of a number. If a single year or a period within a decade is recorded, the appropriate two-character code is repeated to create the four-character code.

          B.C. TABLE                                A.D. TABLE

       1 -   99 d9            2000 -      y
     100 -  199 d8            1900 - 1999 x
     200 -  299 d7            1800 - 1899 w
     300 -  399 d6            1700 - 1799 v
     400 -  499 d5            1600 - 1699 u
     500 -  599 d4            1500 - 1599 t
     600 -  699 d3            1400 - 1499 s
     700 -  799 d2            1300 - 1399 r
     800 -  899 dl            1200 - 1299 q
     900 -  999 d0            1100 - 1199 p
    1000 - 1099 c9            1000 - 1099 o
    1100 - 1199 c8             900 -  999 n
    1200 - 1299 c7             800 -  899 m
    1300 - 1399 c6             700 -  799 l
    1400 - 1499 c5             600 -  699 k
    1500 - 1599 c4             500 -  599 j
    1600 - 1699 c3             400 -  499 i
    1700 - 1799 c2             300 -  399 h
    1800 - 1899 c1             200!
 -  299 g
    1900 - 1999
 c0             100 -  199 f
    2000 - 2099 b9               1 -   99 e
    2100 - 2199 b8
    2200 - 2299 b7
    2300 - 2399 b6                                     
    2400 - 2499 b5                                     
    2500 - 2599 b4                                     
    2600 - 2699 b3                                     
    2700 - 2799 b2                                     
    2800 - 2899 b1                                     
    2900 - 2999 b0                                     
    3000 -      a0                                    

     (i.e., before 2999)                    

In the B.C. table, the letter equals the millennium and the number equals the century. In the A.D. table, the letter equals the century and the number, which must be added, equals the decade.

Examples

661 ##$aw5
Work on the period 1828-1859

661 ##$ao6r2
Work on the period 1066-1328

661 ##$ax8x8
Work on l884

661 ##ax-x-
Work on the 20th century

661 ##$ae-e-
661 ##$ax-x-
Work comparing the 1st century A.D. with the 20th century

661 ##$ad5d6
Work on the period 423 B.C. to 390 B.C.

661 ##$aa0d6
Work on the period to 300 B.C.

661 ##$ap-r-
Work on the 12th to 14th centuries

661 ##$ad9e3
Work on 42 B.C.-A.D. 37

661 ##$ax2x2
Work on 1928

661 ##$av4wl
Work on 1740-1810