Most turns in PDB entries are not classified. As you will see in that list, which I include below, I have added, for each major category of backbone conformation, types of not-specified and other. I'm still not totally happy with this, but I think we are getting closer to something useable. What makes me particularly unhappy ties in with Fran's question of whether we call a helix that is fundamentally alpha but that has a kink in it alpha or other. I've given some thought to how to do this, but I'm not sure which what is the best way to proceed.
Comments are of course welcome.