This field consists of a single-letter date-type, followed by one or two four-digit dates. Most commonly, it will consist of the letter d (monograph, single date of publication) followed by the year of publication.
Monograph published in 1995.
Current periodical, first published in 1984.
Any unknown element of the year is expressed with the letter u, for example:
|a||currently published serial; date 1: first issue, date 2: 9999|
|b||dead serial; date 1: first issue, date 2: last issue|
|c||serial of unknown status; date 1: first issue, date 2: blank|
|d||monograph, complete, published within one calendar year; date 1: publication date, date 2: blank|
|e||reproduction; date 1: publication date, date 2: date of original|
|f||monograph, publication date uncertain; date 1: earliest possible date of publication, date 2: latest possible date of publication|
|g||monograph, publication continues for more than a year; date 1: beginning date of publication, date 2: final date, or 9999 if still in progress|
|h||monograph with both actual and copyright date; date 1: publication, date 2: copyright date|
|i||monograph with both issue date and production date (used for films and music when there is a gap between the production of an item and its release; date 1: issue date, date 2: production date|
|j||monograph with detailed date of publication; date 1, year of publication, date 2: month and day, right justified with zero fill - if the day positions are not used, they hold blanks|