Well, the E. will be east and the S. will be south, so presumably the other numbers are feet or yards calculated from some central point, giving the location of the graves. The Crail sexton, for example, often gave the location of a grave with reference to the so-called Dial Stone, a prominent marker in the graveyard. In Kilrenny churchyard the location of graves was often given with reference to the headstone of the Rev. Brown, a former minister, or to one of the walls or entrances to the churchyard.
Harry