mkref / unref

Hello,

When should I write gdome_xxx_unref( ... ) ?

Should I write unref for each and only each mkref or should
I also write unref when getting object via other method ?

Ex:
void
my_function( void )
{
    GdomeElement* elt = gdome_doc_documentElement( mydoc , &excp );
    // Shoul I write 
    gdome_el_unref( elt , &excp );
    // or not ?
}

Thanks very much

-- 
Laurent Marzullo <marzullo@xxxxxxxxxxxxxxxxxxxxxxxxxxx>