Datum Dimensioning
Datum dimensioning is useful for marking holes and other features on a part. The dimensions are parallel to each other (like chain dimensioning), and have a common datum point. Normally, design engineers use this type of dimensioning for parts that will be NC machined.
The three datum dimension commands are:
• Datum Long -- creates dimensions using long base lines.
• Datum Short -- creates dimensions using short base lines.
• Coordinate -- creates dimensions without dimension lines. Useful if the geometry of the part will cause the dimension lines to be too close together.