Grid_reference_line is an analysis export variable.
It reports the name of the line used as a Line-reference for the depth/range grid of the echogram which was analyzed (m). Layers are numbered with respect to the Line-reference which is specified on the Grid page of the Variable Properties dialog box. The line may be from a line in the EV file or be one of the default lines, "Surface(depth of zero)" or "Transducer face (range of zero)".
This variable is exported only if it is selected on the Export page of the EV File Properties dialog box.
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About Layer_depth_min
About Layer_range_min
About Layer_range_max
About Layer_botttom_to_reference_line_depth
About Layer_botttom_to_reference_line_range
About Layer_top_to_reference_line_depth
About Layer_top_to_reference_line_range