This is the first year I've been following the TdF. I've looked at the website and they have these topo diagrams of each stage but no key to explain what the little numbers in green or red mean. I figured out the one that looks like a fork and spoon <grin>. But I have no idea what the numbers or HC might mean. I'm guessing it's some kind of categorization of the terrain, but I can't tell what exactly.

Any explanation or link to one would be appreciated.