Send me an example of this problem and I will see if I can help -
not sure what you mean, but could be that the face normals are used
to calculate shading, so indices must occur in the correct order
otherwise lighting won't be right (you will see a "black" face instead
of a "lit" face.) Right order meaning right-hand rule gives normal
direction, and normal points out from lit side. This behaviour can
be altered by ShapeHints node to some extent, but best keep all your
normals consistent.
> At any rate, my question is about IndexedLineSet -- my copy of the
> draft 1.0 spec doesn't mention it. Is it part of the spec, or would
> I be one of the horrid non-compliers if I started using it? ;-)
It is in the spec, and has been for a some time as far as I know.
So, you're not going to be on anyone's "dog list" of non-complying sites :)
Tim.