Cartesian grid origin at intersection of central meridian and equator. False easting and false northing. Blue tick marks on topo map border indicate UTM 1,000 meter grid values. Azimuth conversion when using map and compass together. Compass needle aligns with Earth's magnetic field lines at location.
Magnetic declination depends on location wrt magnetic north pole.
Magnetic north pole wanders. Determining magnetic declination using map, compass, and terrain features. Azimuth determination and conversion precautions. 150 yards off after one mile of travel. Magnetic declination error - depends on users location wrt magnetic north pole.