In Italian, the gender is marked by the ending: -a fem; -o
masc.
Nouns exist which
- form the
feminine by adding -essa: conte/contessa vs. il/la
giudice;
- express the gender alternation with ``eteronymia":
they are nouns in which the semantic features [+masc] and [+fem] are
lexicalized, uomo/donna, padre/madre.
- have
the same form for masculine and
feminine:
``epiceni" nouns, il/la tigre.
The pertinent values are masculine, feminine and
common, i.e. the same morphological form for masculine
and feminine, typical of Romance languages.
The value common can be seen as a multilabel whose semantics
is a ``disjunction" operation:
in fact, the value c is a macro for m 
f.
It is used for the lexicon encoding of
the series of common nouns which have the same form for masculine and
feminine.
For these classes of nouns, the gender can be decided only in the context on the basis of syntactic considerations, i.e. by observing the gender of the agreed article and adjective: un bravo insegnante, una ottima insegnante. Sometimes the context cannot be sufficient to solve the underspecification and the gender remains undecided: insegnanti capaci affollano quella scuola.