SplineStart Row (Geometry Section)
Contains x and ycoordinates for a spline's second control point, its second knot, its first knot, the last knot, and the degree of the spline.
A SplineStart row contains the following cells.
Cell  Description 

The xcoordinate of a spline's second control point. 

The ycoordinate of a spline's second control point. 

The second knot of the spline. 

The first knot of a spline. 

The last knot of a spline. 

The degree of a spline (an integer from 1 to 25). 
Remarks
Visio displays the definition of a spline in a Geometry section that contains a SplineStart row followed by one or more SplineKnot rows. The SplineStart row must be preceded by another kind of row, such as a MoveTo row, to indicate the first control point of the spline. The preceding row can be a LineTo, ArcTo, NURBSTo, PolylineTo, or EllipticalArcTo row if the spline follows a segment of that type.