18. The computer-readable memory device of claim 15 , wherein: the at least one normalization instruction of the selected normalization rule further comprising compiled code; and applying the at least one normalization instruction of the selected normalization rule to the expression further comprises: invoking the compiled code of the selected normalization rule on the expression.
15. A computer-readable memory device not consisting of a propagated data signal, the computer-readable memory device storing instructions that, upon execution on a processor of a computer, cause the computer to translating expressions, by: applying to the expression a temporal translation grammar comprising: at least one recognition rule respectively identifying a temporal element of an expression; at least one normalization rule respectively normalizing a temporal element of the expression to a normalized temporal element; and at least one translation rule respectively translating a normalized temporal element into a date; wherein the temporal translation grammar is operable for use in a first translation context and a second translation context, wherein the first translation context is different from the second translation context.