Chapter 6  ENTITIES Section
DIMENSION 
Radial and Diameter Dimension Group Codes

The following group codes apply to radial and diameter dimensions. In addition to the group codes described here, those listed in "Common Group Codes for Entities" and "Common Dimension Group Codes" can also be present. For information about abbreviations and formatting used in this table, see "Formatting Conventions in This Reference."
Radial and diameter dimension group codesGroup codes  Description 
100 
Subclass marker (AcDbRadialDimension or AcDbDiametricDimension) 
15 
Definition point for diameter, radius, and angular dimensions (in WCS) 
25, 35 
DXF: Y and Z values of definition point for diameter, radius, and angular dimensions (in WCS) 
40 
Leader length for radius and diameter dimensions 
The point (15,25,35) specifies the first point of the dimension line on the circle/arc and the point (10,20,30) specifies the point opposite the first point. The point (11,21,31) specifies the midpoint of the dimension text.
The point (15,25,35) specifies the first point of the dimension line on the circle/arc and the point (10,20,30) specifies the center of the circle/arc. The point (11,21,31) specifies the midpoint of the dimension text.