Ordinate dimensions are a set of dimensions measured from a zero ordinate in a drawing or sketch. In drawings, they are reference dimensions and you cannot change their values or use the values to drive the model.
Ordinate dimensions are measured from the axis you select first. The type of ordinate dimension (horizontal or vertical) is defined by the orientation of the points you select.
Example: Ordinate Dimensions
You can dimension to edges, vertices, and arcs (centers and minimum and maximum points). You can also dimension to midpoints when you add ordinate dimensions.
Ordinate dimensions are automatically grouped to maintain alignment. When you drag any member of the group, all the members move together. To disconnect a dimension from the alignment group, right-click the dimension, and select Break Alignment.
You can drag the zero dimension to a new position, and all the ordinate dimensions update to match the new zero position.
If adjacent dimensions are very close together, the leaders are automatically jogged as needed to prevent overlapping text. Drag handles are displayed at the bends when you select an ordinate dimension with a bent leader. You can remove the bend, or add a bend to a different ordinate dimension.
You can set ordinate dimension document properties in Document Properties - Ordinate Dimensions. You can specify that the leaders not be automatically jogged by clearing Automatically jog ordinates.