z k 1 the setup of this coordinate system is described immediately hereinafter referring to fig3 c in conjunction with fig1 and 2 the origin and directions of the x y z coordinate system can be specified in relation to drill begin point 1 and target t the location where drilling begins is a convenient choice for the origin and the direction from this position to the projection of the target onto a level plane through the origin defines the x coordinate axis the z coordinate axis is positive upward and the y coordinate axis completes a right handed system if desired a different right handed cartesian coordinate system or any suitable coordinate system may be used in the present example the formulation constrains the x axis to be level as noted above yaw orientation is designated as u03b2 measured from the x axis in a level x y plane whereas pitch orientation is designated as u03c6 measured vertically from the yawed tool position in the x y plane as represented by a dashed line in the x y plane fig3 c defines pitch and yaw as euler angles that require a particular sequence of yaw and pitch rotations in order to rotate the steering tool from a hypothetical position along the x axis into its illustrated position the use of an electronic distance measurement device edm is currently the quickest and most accurate method of defining the x coordinate axis and measuring magnet position coordinates however.