Checkout, put, checkin

Hi,

There's something I find strange for a long time about the chekout-put-checkin mechanism :
first, you CHECKOUT the resource you want to modify (OK... but you GET it it the same time I suppose... no ?)
then, you PUT the modified resource (arg ! that, I can't imagine it : where is this new resource, since it may not overwrite the old one ?)
and then you CHECKIN the resource, so that the server records it as a new version...

I seem maybe very stupid, but I don't care ;o)

Thanx