A careful examination of the location of variation in the grammar is advocated as opposed to attempts to cover linguistic generalizations with a single rule. Such an examination may lead to non-deterministic solutions, since there may be two distinct possible derivations for a single surface structure. For instance, in Portuguese, the variation found in the phrase "as casa branca" could result from plural marking throughout followed by deletion of the final two -s's, or from non-application of the plural marking rule in the case of one or both of the last two words. A multiple rule solution may provide no way of distinguishing which rules did or did not apply to produce a given utterance. This approach, unlike extremely complicated rules which attempt to cover all variations, honors the basic concept of separate grammatical levels. (Author/JB)