A hatch my have "holes", if it eg. is made of two forms, an inner form, and and outer form, where the outer form is filled while the inner form appears like a window inside of the fill, that lets the background be seen.

QCAD exports such hatches as two SVG paths in one single entity. But the "hole" is lost in the process. I know of two workarounds, that preserve the original intention of the QCAD drawing, both get the same result most of the time, the second one looking more robust and easier to implement:

# draw the outer form clockwise, draw the inner form counterclockwise
# set the "fill-rule:evenodd" attribute on the fill definition of the entity

Drawing a star like in the SVG spec in QCAD actually produces the same picture -- so that should be the way to go.

http://www.w3.org/TR/SVG/painting.html#FillRuleProperty