Ordinate dimensions are used to measure the perpendicular distance from an origin point called the datum to a feature, such as a hole in a part. Ordinate dimensions are comprised of a leader line with an X or Y value. These dimensions are called datum dimensions. X or Y value is calculated in the current UCS, and leaders are drawn along the orthographic direction at the current UCS. The dimension values are the absolute values. By maintaining accurate offsets of the features from the datum, these dimensions can prevent escalating errors.
X ordinate dimensions show the distance of a feature from the datum along the X axis. And Y ordinate dimensions show the distance along the Y axis. The system determines whether the dimension is X or Y ordinate dimension depending on the point you specify. If the distance is greater for the Y value, the system creates an X ordinate dimension. Otherwise, the system creates a Y ordinate dimension.
X and Y ordinate values are determined by the absolute coordinate value of the current UCS. Before creating ordinate dimensions, it recommends you to reset the UCS origin to coincide with the datum.
In ordinate dimensions, the dimension text is always aligned with the ordinate leader line, ignoring the text orientation defined by the current dimension style. You can also supply your own text or accept the default one.
To create an ordinate dimension
Choose Dimensions > Ordinate.
Select the point for ordinate dimension.
Specify the ordinate leader endpoint.
Command line DIMORDINATE
Select the ordinate point (A), and then specify the ordinate leader endpoint (B).
TIP To select precise ordinate points, use entity snaps.
DIMORDINATE: Creates ordinate point dimensions
System Variables Reference