Add ordinate dimensions to a drawing to measure the distance from an origin point to multiple reference points along an element.
- Click Annotate tab
Dimension panel 
(Aligned) or 
(Linear). - In the Type Selector, select an ordinate dimension style.
- In the drawing area, select the first point (origin) for the dimension.
- Continue to select the necessary reference points.
- When you have reached the last reference point, move the cursor away from the last element, and click.
The ordinate dimension displays.