There are several types of coordinate systems you can use, and you can switch between them at any time.
For example, when drawing the outer wall of a house, you may want to start the first wall at an absolute location. Each successive wall, however, will be defined by its length and angle relative to the first wall, so you would use polar coordinates for these points. To place walls at an X, Y distance from any other point, you could use relative coordinates.
You can display the Coord System toolbar by right-clicking in any toolbar area and selecting Coord System.
Coordinates, when entered manually, are entered in the Coordinate Fields, at the lower right corner of the screen. See Coordinate Fields. You can press Shift+Tab to jump to the first field in the Coordinate Fields, then press Tab to scroll through the remaining fields.
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