s.  The second argument,
   if present, must be type <TT
CLASS="TYPE"
>integer</TT
>; it receives the type
   modifier associated with the destination type, or -1
   if there is none.  The third argument,
   if present, must be type <TT
CLASS="TYPE"
>boolean</TT
>; it receives <TT
CLASS="LITERAL"
>true</TT
>
   if the cast is an explicit cast, <TT
CLASS="LITERAL"
>false</TT
> otherwise.
  </P
><P
>   It is legitimate to create a <TT
CLASS="STRUCTNAME"
>pg_cast</TT
> entry
   in which the source and target t