The purpose of date normalization is to allow for a general date search function in the APIS interface.

The tables to the left show sample textual "modern dates" from Phase II APIS records, along with the normalized date equivalents that were either automatically generated or hand-edited from them for loading into the central APIS database.

*BCE: Use minus sign for BCE dates

*For items dated to a specific year, enter that year in Date1 and leave Date2 blank, e.g. "ca. 257 B.C."
   dd046 | 1 | = -257
   dd046 | 2 | =

* For items known or likely to be from within a span of dates, put the earliest possible date as Date1 and the latest possible date as Date 2, e.g., "Between 180 and 192 A.D"
      dd046 | 1 | = 180
      dd046 | 2 | = 192

* CE: for items originating within a span of dates within a single century, if actual dates are not used, use the following approximations:

-"Early"
     dd046 | 1 | = [YY]00
      dd046 | 2 | = [YY]25
-"1st half"
      dd046 | 1 | = [YY]00
      dd046 | 2 | = [YY]50
-"Middle"
      dd046 | 1 | = [YY]50
      dd046 | 2 | =[none]
-"2nd half"
      dd046 | 1 | = [YY]50
      dd046 | 2 | = [YY]99
-"Late"
      dd046 | 1 | = [YY]75
      dd046 | 2 | = [YY]99

* CE: For items dated to within a single CE century, use the beginning and end dates of the century. For the beginning date, start with the zero year (except for 1st Century CE, for which begin with "1"), e.g., "VIIth cent. A.D."
      dd046 | 1 | = 600
      dd046 | 2 | = 699

* BCE: for items originating within a span of dates within a single century, if actual dates are not used, use the following approximations:

-"Early"
     dd046 | 1 | = -[YY]99
     dd046 | 2 | = -[YY]75
-"1st half"
      dd046 | 1 | = -[YY]99
      dd046 | 2 | = -[YY]50
-"Middle"
      dd046 | 1 | = -[YY]50
      dd046 | 2 | = -[none]
-"2nd half"
      dd046 | 1 | = -[YY]50
      dd046 | 2 | = -[YY]00
-"Late"
      dd046 | 1 | = -[YY]25
      dd046 | 2 | = -[YY]00

* BCE: For items dated to within a single BCE century, use the beginning and end dates of the century. For the beginning date, start with the 99th year; for the end date, use the zero year (except for 1st Century BCE, for which begin with "1"), e.g., "IIIrd cent. B.C."

     dd046 | 1 | = -299
     dd046 | 2 | = -200