>src</TT
> result is what was copied while the
       <TT
CLASS="PARAMETER"
>dest</TT
> result is the copy destination.  This event
       can be used to provide a deep copy of <TT
CLASS="LITERAL"
>instanceData</TT
>,
       since <TT
CLASS="LITERAL"
>PQcopyResult</TT
> cannot do that.  If the event
       procedure fails, the entire copy operation will fail and the
       <TT
CLASS="PARAMETER"
>dest</TT
> result will be cleared.   When returning a
       failure code, all cleanup must be performed as no
  