The GM_LineVolumeParams_t type exposes the following members.
Width (i.e. diameter) in meters of corridor around line in which to calculate volume
Cut heights for each point in meters
Are the cut heights in mCutHeights relative to sea level (TRUE) or ground level (FALSE)
List of points in line in global coordinate system
Size of structure
Sample spacing in the x direction in global units
Sample spacing in the y direction in global units