The purpose of this document is to provide guidance for the measurement of the electric field strength, ion-current density, conductivity, monopolar space-charge density, and net space-charge density in the vicinity of high-voltage dc (HVDC) power lines, in converter substations, and in apparatus designed to simulate the HVDC power line environment. The document defines the terms that are used, describes the interrelationship between electrical parameters, describes operating principles of measuring instruments, suggests methods of calibration where applicable, describes measurement procedures, and identifies significant sources of measurement error.<<ETX>>