The relation between Scouts and brain grid

Dear Francois;
I'm going to know that what is the relation between scouts coordinates (for example 54_135_120)
Capture1
and GridLoc arrays.
For instance, if I want to simulate one of the scout's effects on a certain electrode on the scalp, I need to know which row of Leadfeild matrix (array of OpenMEEG BEM.GridLoc) is related to scout location and electrodeposition.
When I check the GridLoc arrays, their values are not related to scouts' location values (54_135_120)!
where am I wrong?

Wishes
Morteza