Global inside a Function

Well thats me blown out of the water.

Does that mean you cannot re-allocate a global within a function?

If so is a global in a function a gloryified const?
To use a Global as a real changeable variable Do I need to declare it out side a function?
If I declare it as a field within a type, can I change it, or am I stuck with only the original value?

edit
Test:+1 works though dosent it? Even in Functions, so its only the declareation that is run once. O.K. I get it. Mind It would probably count 1,2,2,3 or something ;)

Thanks