The following group codes apply to spline entities.
Spline group codes 


Group code 
Description 
100 
Subclass marker (AcDbSpline) 
210 
Normal vector (omitted if the spline is nonplanar) DXF: X value; APP: 3D vector 
220, 230 
DXF: Y and Z values of normal vector (optional) 
70 
Spline flag (bit coded): 1 = Closed spline 2 = Periodic spline 4 = Rational spline 8 = Planar 16 = Linear (planar bit is also set) 
71 
Degree of the spline curve 
72 
Number of knots 
73 
Number of control points 
74 
Number of fit points (if any) 
42 
Knot tolerance (default = 0.0000001) 
43 
Controlpoint tolerance (default = 0.0000001) 
44 
Fit tolerance (default = 0.0000000001) 
12 
Start tangent—may be omitted (in WCS) DXF: X value; APP: 3D point 
22, 32 
DXF: Y and Z values of start tangent—may be omitted (in WCS) 
13 
End tangent—may be omitted (in WCS) DXF: X value; APP: 3D point 
23, 33 
DXF: Y and Z values of end tangent—may be omitted (in WCS) 
40 
Knot value (one entry per knot) 
41 
Weight (if not 1); with multiple group pairs, they are present if all are not 1 
10 
Control points (in WCS); one entry per control point DXF: X value; APP: 3D point 
20, 30 
DXF: Y and Z values of control points (in WCS); one entry per control point 
11 
Fit points (in WCS); one entry per fit point DXF: X value; APP: 3D point 
21, 31 
DXF: Y and Z values of fit points (in WCS); one entry per fit point 