Define custom unit for Ruler
You can define and use custom units in the Ruler. To define a new custom unit use the corresponding dialog called either from the ruler context menu or directly by a left mouse double-click in the ruler's unit pane (the pane displaying the unit label). The custom units can be also saved under arbitrary names and then selected under the Select Custom unit submenu of the ruler context menu. For quick access to the custom units use the context menu of the ruler's unit pane.
The Define custom unit for Ruler dialog contains the following sections: