In Pedantic Mode;
Degrees, minutes and tenths of a minute only I would have thought. This is the maximum resolution possible for manual data entry into the aircraft inertial navigation system.
The onboard Flight Management System usually knows the position of each stand on each airport . So the display painted on the blackboard is a further crosscheck to the Jeppesen and the FMS.
Once the initial starting position is entered correctly the inertial navigation system will calculate the aircraft's position thereafter with impressive accuracy.