Catline, Cathead : Catline is a line powered by the cathead, which is a concave, rotating, pulley-type device mounted on the end of a shaft of the drawworks. Catlines are used to lift or pull equipment around a rig. (RP 54)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}