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
Control-point 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)
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
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
21, 31
DXF: Y and Z values of fit points (in WCS); one entry per fit point