Channel maps of the ¹²CO(2−1) emission between  − 23 and  − 15 km s^-1 in steps of 1 km s^-1. The central velocity of each panel is given in the upper left-hand corner. Lowest contour 2 K km s^-1, step size 4 K km s^-1; contours of 10 K km s^-1 and higher are white. The cross at offset (0, 0) marks the location of the exciting star of Sh 2-217, while the ellipse shows the outline of the optically-visible H ii region.