libpq PQftype() to comprehend types?

Can someone tell me how I can use PQftype() or some other mechanism to
interpret a query result in terms of the data types of the columns?


I need to be able to tell what data type a given column is. The 6.3.2
manual says PQftype() returns an internal coding -- is this defined in a
header file I can access, or ... ?

thanks,
Michael