Before revision: T: 086 ° V: +3° M: 089° D: +4 ° C: 093° Thus, when following a compass course of 093°, the true course is 086°.
After revision: T: 092 ° V: +3° M: 089° D: -4 ° C: 093° Thus, when following a compass course of 093°, the true course is 086°.