The Declination in the Project Settings dialog can be used for azimuth correction. This is typically used to correct for magnetic declination, but can be used to adjust to grid north.
If you have already adjusted your measurements with your compass, then leave the default value of 0 (zero) declination, since additional correction is not required.
NOTE: The declination is ADDED to all azimuth values, so use:
a POSITIVE value to correct for EAST declination
a NEGATIVE value to correct for WEST declination
e.g. a Declination of –7 indicates a declination of 7 degrees WEST
Declination for Borehole Traverse Type
If you are using Borehole Traverses, and if borehole trends (azimuths) are taken from grid north, you must use ZERO Declination. The Declination, if non-zero, will be applied to the borehole trends (azimuths). This is the Orient 3 value in the Traverse Information dialog.
Declination for Clinorule Traverse Type
If you are using Clinorule Traverses, and if clinorule drift orientations (reference lines) are taken from grid north, you must use ZERO Declination.