See 7.2 Doc $ 12.2.3
"In the present release of PostgreSQL there are some unpleasant restrictions
on how functions returning composite types can be used. Briefly, when
calling a function that returns a row, we cannot retrieve the entire row. We
must either project a single attribute out of the row or pass the entire row
into another function. (Trying to display the entire row value will yield a
meaningless number.) "
___________________________________________
Jacques Massé
Tel. 33 (0)5 57 89 08 11 - Fax 33 (0)5 57 89 08 01