  A model for the full treatment of Spanish inflection for verbs, nouns and
adjectives is presented. This model is based on feature unification and it
relies upon a lexicon of allomorphs both for stems and morphemes. Word forms
are built by the concatenation of allomorphs by means of special contextual
features. We make use of standard Definite Clause Grammars (DCG) included in
most Prolog implementations, instead of the typical finite-state approach. This
allows us to take advantage of the declarativity and bidirectionality of Logic
Programming for NLP.
  The most salient feature of this approach is simplicity: A really
straightforward rule and lexical components. We have developed a very simple
model for complex phenomena.
  Declarativity, bidirectionality, consistency and completeness of the model
are discussed: all and only correct word forms are analysed or generated, even
alternative ones and gaps in paradigms are preserved. A Prolog implementation
has been developed for both analysis and generation of Spanish word forms. It
consists of only six DCG rules, because our {\em lexicalist\/} approach --i.e.
most information is in the dictionary. Although it is quite efficient, the
current implementation could be improved for analysis by using the non logical
features of Prolog, especially in word segmentation and dictionary access.
