manual…

square_2d.geo
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			// Element size
			h = 0.05;

			// Dimension of square
			L = 1;

			// ------------------------------------------
			// Geometry
			// ------------------------------------------

			// Points
			Point(1) = {0, 0, 0, h};
			Point(2) = {L, 0, 0, h};
			Point(3) = {L, L, 0, h};
			Point(4) = {0, L, 0, h};

			// Lines
			Line(1) = {4, 1};
			Line(2) = {1, 2};
			Line(3) = {2, 3};
			Line(4) = {3, 4};

			// Geometric and Physical Surface
			Line Loop(6) = {4, 1, 2, 3};
			Plane Surface(6) = {6};
			Physical Surface(7) = {6};