Spoken text

There are three different axes around which the turtle can rotate. These are the up-, left- and head-axis. The axes build a right-angled, three-dimensional coordinate system, which is carried along by the turtle. The turtle commands RL, RH, and RU cause rotations around the three different axes.
To illustrate this in GroIMP, at first two elongated cuboids are drawn in two different colors directly next to each other. To rotate the second box, you have to set the rotation command with the degree indication of the rotation angle ahead of the command for the second box. So the turtle is turned in the corresponding direction, thereby the subsequent object is drawn in that direction.
RU causes the second cuboid to rotate around the up-axis. By the RL command it rotates around the left axis. RH rotates the second box around the head-axis or rather around itself.