Currently, Lines.mask creates a mask by interpolating the bottom points on the coordinates of the Sv data array and doing a "if below point, then Sv value is bottom, else if not" operation
From looking through Echoview, we have realized that it does the same region masking operation as that of regionmask (and Regions2D.mask)
Lines.maskcreates a mask by interpolating the bottom points on the coordinates of the Sv data array and doing a "if below point, then Sv value is bottom, else if not" operationregionmask(andRegions2D.mask)regionmask