Six-character unique alphanumeric code
that permanently identifies a serial publication
(such as a journal
or magazine) or non-serial publication (such as a dissertation
or thesis). For example, JECLB3 is the Coden for the 'Journal Of Economic Literature,' LANCAO for the journal 'Lancet,' and NATUAS for the journal 'Nature.' The first four characters of a Coden are always letters that make up a mnemonic
for the publication, the fifth is a distinction character
from A to F), and the sixth (a letter from A to Z, or a number from 0 to 9) is a computed check-character that helps in identification of typographical mistakes in the code.
Although this system
by the American Society For Testing
& Materials (ASTM) and the code is assigned by the Chemical Abstracts Service (CAS), it covers publications in all subject areas.