The ADS uses bibliographic codes (bibcodes) to identify literature in our database. Using a standard bibliographic format, as explained below, we can easily identify different articles and users can efficiently search for them. The bibcode is a 19 digit identifier which describes the journal article. The format was originally adopted by the SIMBAD and NED projects, and follows the syntax: YYYYJJJJJVVVVMPPPPA where:

• YYYY: Year of publication
• JJJJJ: A standard abbreviation for the journal (e.g. ApJ, AJ, MNRAS, Sci, PASP, etc.). A list of abbreviations is available.
• VVVV: The volume number (for a serial) or an abbreviation that specifies what type of publication it is (e.g. conf for conference proceedings, meet for Meeting proceedings, book for a book, coll for colloquium proceedings, proc for any other type of proceedings).
• M: Qualifier for publication:
  • E: Electronic Abstract (usually a counter, not a page number)
  • L: Letter
  • P: Pink page
  • Q-Z: Unduplicating character for identical codes
• PPPP: Page number. Note that for page numbers greater than 9999, the page number is continued in the m column.
• A: The first letter of the last name of the first author.

The fields are padded with periods (.) so that the code is always 19 characters long. The journal is left-justified within its 5 characters, and the volume and page are right-justified. New journal abbreviations should be unique, and follow existing naming conventions. As an example, the bibliographic code: 1992ApJ…400L…1W corresponds to the article: Astrophysical Journal Letters volume 400, page L1.