Bowtie quads within official parts

[Philippe Hurbain]

It would be certainly interesting to have the list... and it's even better if you can provide a fix to the files themselves. But be aware that files that have bowtie quads generally have other flaws, as they are early parts issued before "modern" rules:
- they are not BFCed
- they may contain non-planar quads
- they may contain primitives with degenerated transformation matrix.