Horizontal Dimensions
You can dimension in the horizontal plane irrespective of the position of the dimension points.
To dimension in the horizontal plane:
1. Click Linear in Dimensions.
2. In Linear, click the applicable datum dimension command (Datum Long or Datum Short or Coordinate).
3. Click Horizontal.
4. Click a single dimension point. This becomes the common datum point.
5. Click one or more additional dimensioning points.
6. If you switched Automatic dimension placement off in Options under Dimension Settings, click the desired location for the dimension text(s), using the dimension trace for guidance.
7. To add more dimensions relative to the common datum point, select additional drawing elements.