With 2.18 the commands setCompassDeclination and setCompassOscillation were introduced.
I have received a request for my mod "DUI - Squad Radar" to simulate the changes these two commands do. While looking up these new commands in the Biki, i noticed a lack of getter commands for these.

Examples how to use:

setCompassDeclination rad 90;
private _declination = deg getCompassDeclination;
systemChat str _declination;
// writes "90" into chat

setCompassOscillation [rad 90, 1, 2];
getCompassOscillation params ["_rad, _min, _max];
systemChat format ["%1 %2 %3", deg _rad, _min, _max];
// writes "90 1 2" into chat