About Zones for Linear and Angular Dimensions
The zone is a theoretical area defined by the boundaries of the entities that you select for dimensioning. By default, the dimension text of a created dimension, linear or angular, is centered about its distance between the witness lines if it fits between its witness lines and is placed within the zone.
Zone for Linear Dimensions
1. Selected reference
• 
Zone
Zones for Angular Dimensions
For angular dimensions, the dimension text is always within one of the four zones,
based on the location you select. The minimum selection zone for an acute angle dimension is 15 degrees, centered about the theoretical centerline of the angle.
The figure below shows the different zones for angular dimensions.
• In the figure, a 5-degree angular dimension is created by the 2 red lines.
• If you select a placement point within the selected entities, (the area in magenta in the figure), the 5-degree dimension is created and placed within the entities based on the rules for automatic placement of dimensions.
• If you select a placement point outside the 5-degree zone but within the 15-degree zone as indicated by area in green in the upper part of the figure, then the 5-degree dimension is created and placed at the selected point.
• If you select the placement point outside the 15-degree zone as indicated by the areas in orange and blue, then 175-degree dimensions are created and placed based on the rules for automatic placement of dimensions.
• If you select the placement point within the 15-degree zone opposite the selected entities, as indicated by the area in green in the lower part of the figure, then a 355-degree dimension is created and placed based on the rules for automatic placement of dimensions.
