I see that Maretron’s DSM150, DSM200, and DSM250 displays have a SSC200 configuration setting called "Installation Offset Calibration?"; what is this?

Maretron’sDSM150, DSM200, and DSM250 displays have a SSC200 configuration setting called "Installation Offset Calibration...", which is used to electronically align the compass with the vessel. Although there is an arrow on the compass label, it is difficult to exactly align the compass with the vessel during installation. This configuration setting allows the compass to be precisely aligned with the vessel.