[Freesurfer] Gray matter volume calculation

Dear Freesurfer team,

We are analyzing the gray matter volume of some customized labels, using mris_anatomical_stats.

We are wondering about some characteristics of the obtained volume.

Is the volume of a label (as calculated by mris_anatomical_stats) the sum of the volume elements of each vertex contained in that label (considering the volume elements per vertices stored in the file '?h.volume' inside the 'surf' folder)?

Is the 'volume element per vertex' (?h.volume) calculated from the 'white surface area element per vertex' (?h.white), 'pial surface area element per vertex' (?h.pial) and 'thickness element per vertex' (?h.thickness) ?

What would be the formula to calculate 'volume element per vertex'?

Bests,

Josue