Dumb question - GLclampf - why?

Just looking more closely at glClearColor and it takes four GLclampf parameters. GLclampf resolves down to float on my PC. I was wondering what the design purpose of GLclampf is - and whether other implementations take advantage of this facility?

GLclampf is a value clamped to 0 and 1, and is of type float… look up gl documentation for the official description, but i think thats it…