Hollow Grinding A Knife

Another video that will hopefully take some of the mystery out of knife making.

http://www.youtube.com/watch?v=iWLz3EgEa00

Very interesting. But what is hollow that makes it "hollow grind"?

This picture will show some of the different grind profiles.

http://i312.photobucket.com/albums/l...rt/grinds1.jpg

Ah ok. Thanks.