D Cell (Geometry Section)
Represents different information in different rows. This table describes the D cell based on the row in which it's located.
Row  Description 

EllipticalArcTo 
The ratio of an arc's major axis to its minor axis. Despite the usual meaning of these words, the "major" axis does not have to be greater than the "minor" axis, so this ratio does not have to be greater than 1. Setting this cell to a value less than or equal to 0 or greater than 1000 can lead to unpredictable results. 
NURBSTo 
The first weight of the nonuniform rational Bspline (NURBS). 
SplineStart 
The degree of a spline (an integer from 1 to 25). 
Ellipse 
A y coordinate of a point on an ellipse; paired with the x coordinate represented by the C cell. 
Remarks
To get a reference to the D cell by name from another formula, or from a program using the CellsU property, use:
Cell name: 
Geometry i .D j where i and j = <1>, 2, 3... 
Geometry i .D1 (Ellipse row) where i = <1>, 2, 3... 
To get a reference to the D cell by index from a program, use the CellsSRC property with the following arguments:
Section index: 
visSectionFirstComponent + i where i = 0, 1, 2... 
Row index: 
visRowVertex + j where j = 0, 1, 2... 
visRowVertex (Ellipse row) 

Cell index 
visAspectRatio (EllipticalArcTo row) 
visNURBSWeightPrev (NURBSTo row) 

visSplineDegree (SplineStart row) 

visEllipseMinorY (Ellipse row) 