Definition of Production

Hi all,

I'm looking for a clear definition of `production' in a (computer)
grammatic/syntactic context. I've seen it used to mean anything from
rule (in the xBNF sense) to input string, to mixtures of both
(e.g. the segment of the input that matched a given rule).

I would like to know if there is more precise definition, and an
example or two if possible :). A related question is whether
`production' == `production rule'. Thanks in advance for the help.

Cheers,
-Al-
[No terms in comp sci have precise definitions, but I've consistently
seen production used in the sense of a grammar rule. -John]

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