Swiveling : The rotation of the load attachment portion (hook or shackle) or a load block (lower) or hook assembly about its axis of suspension in relation to the load lines(s). (Spec 2C)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}