19.1.3 Abbreviations

BGGM = British Geological Survey Global Geomagnetic Model
HLA = Highside – Lateral – Alonghole Co-ordinate system
IFR = In Field Referencing
IPM = Instrument Performance Model
IGRF = International Geomagnetic Reference Field
ISCWSA = Industry Steering Committee for Wellbore Survey Accuracy
MWD = Measurement Whilst Drilling
NEV = North – East – Vertical Co-ordinate system
RSS = Root Sum Square
SPE = Society of Petroleum Engineers