Font Validator is a tool for testing fonts prior to release. This testing ensures that fonts meet Microsoft's high quality standards and perform exceptionally well on Microsoft's platform.
There is a clarification for svgDoc to allow doc reuse - i.e. later glyph index ranges re-using earlier svgDoc. Needs checking that's supported, or code needs to be enhanced.
validation based on a cached DTD or other similar mechanism (network access much not be required, nor on-the-fly fetch from w3c)
checking cross-references against CPAL.
A very distant plan may be to try rendering and catches rendering errors, in the same way one does in the rasterization tests for truetype fonts.