SVG Tiny 1.2 specification: Non-scaling stroke

I'm not sure about 11.5 Non-scaling stroke
"stroke outline shall be calculated in the "host" coordinate space"

Is the host space just the transformation U or U x VB (what I would 
expect from the png image showing the result of the example 
non-scaling-stroke.svg 
<http://www.w3.org/TR/SVGTiny12/examples/non-scaling-stroke.svg>)? But 
i.e. Firefox 21 seems to use just U (and the center line width is not 
1/9 of the others lines).

cu Martin