Units: Note that Dexter uses the metric system of measurement. So all units of distance are in meters. A meter is about 3 feet which is about Dexters full reach at the size Dexter has been made at so far. A tenth of a meter (e.g. 0.1) is about 4 inches which is about the length of your finger. A hundredth of a meter (e.g. 0.01) called a "centimeter" is a about a half inch (actually closer to 0.4 inches) or about the width of your little finger. And a thousandth of a meter (e.g. 0.001) called a "millimeter" is tiny, about a half of a tenth of an inch or about the thickness of a fingernail.
So if you change the first digit to the right of the decimal point, you are moving about a finger length. The next digit, 2nd to the right, moves you about a finger width, and the 3rd moves you about the thickness of a fingernail.
It also appears in the upper right pane of the app itself.
To download and install DDE, see User Guide/Installation below.