Refer back to the compass rose in Post #74. A marine or aviation chart of a different area will have different info in the center....different variation and different annual increase and/or decrease in this variation. Your compass will point to Magnetic North but the difference between Mag. North and True North changes dependent on your position on the globe.
Mariners discovered this ages ago when they found that their compasses did not always point to Polaris. If you go here and enlarge some of the roses, you will see the differences in the info at the center.
Thanks!