This field should not be confused with the key that appears in the The number of a journal, magazine, technical report, or of a work in a series.
An issue of a journal or magazine is usually identified by its volume and number; the organization that issues a technical report usually gives it a number; and sometimes books are given numbers in a named series.
The Chicago Manual of Style , on the other hand, espouse the author-date system, in which the citation might appear in the text as `(Jones, 1986)'.
I argue that this system, besides cluttering up the text with information that may or may not be relevant, encourages the passive voice and vague writing.
Finally, the logical deficiencies of the author-date style are quite evident once you've written a program to implement it. (I have, unfortunately, programmed such a style, and if you're saddled with an unenlightened publisher or if you don't buy my propaganda, it's available from the Rochester style collection.) Ok, so the spiel wasn't very brief; but it made me feel better, and now my blood pressure is back to normal.
For example, in a large bibliography, using the standard alphabetizing scheme, the entry for `(Aho et al., 1983b)' might be half a page later than the one for `(Aho et al., 1983a)'. Here are the tips for using with the standard styles (although many of them hold for nonstandard styles, too).
Therefore, database entries of different types have different fields.
For each entry type, the fields are divided into three classes: Omitting the field will produce a warning message and, rarely, a badly formatted bibliography entry.
Furthermore the strongest arguments for using the author-date system--like ``it's the most practical''--fall flat on their face with the advent of computer-typesetting technology.
For instance the Chicago Manual contains, right in the middle of page 401, this anachronism: ``The chief disadvantage of [a style like TEX, obviously, sidesteps the disadvantage.