External Guylines : Lines which provide stability and run from some point in the derrick, mast, or pole to ground anchors or to a special substructure or derrick base which provides a substitute for ground anchors. (RP 54)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}