In constrast with Nêlêmwa (Oceanic, New Caledonia) whose lexemes are most generally subcategorised as nouns or verbs and undergo category-changing derivations, in Amis (Formosan), roots are pervasively categorially neutral, yet they contain semantic features and instructions that allow or disallow combination with primary derivational affixes which specify their class and category. Lexical categories are expressed after derivation from roots to become morphosyntactic words projected in a syntactic frame; they are then quite rigidly subcategorised as verbal, nominal or adjectival-modifying heads. Still, word forms display some functional flexibility; for instance, nouns and derived nouns, pronouns, numerals may be predicative in equative, ascriptive and focus constructions, simply by being in the syntactic position of the verb. Such functional flexibility is asymmetrical and does not apply to derived verb stems which must be nominalised to achieve argument function.