stretchpoint issues

The spec says:

  "The draw:path-stretchpoint-x and draw:path-stretchpoint-y attributes
   specifies the stretchpoint of a shape."

I happen to know that the stretchpoint is the same as the VML
"limo-stretch point". This is what the VML spec says:

  "The limo-stretch definition and the formulas element (described
   below) allow greater designer control of how the path scales.  They
   allow, for example, definition of a true rounded corner rectangle
   where the corners remain circular even though the rectangle is scaled
   anisotropically."
   See: http://www.w3.org/TR/1998/NOTE-VML-19980513

In neither spec is it described how the stretchpoint actually affects
the calculation of the shape's vertices. While the formulas can
reference the stretchpoint, it is easily demonstrated that the
stretchpoint has an additional undocumented effect.

Also, while the stretchpoint is defined relative to the svg:viewBox
coordinate system, the spec does not mention that. In fact, svg:viewBox
says only "this user coordinate system is used by the svg:points
attribute and the <draw:path> element".

Thanks,
Chris