[Paraview] Sum of cell value

[Bastil2001 at yahoo.de]

I need to sum of a cell value over all cells. I guess this is possible
using a Python Calculator but I don't know how? Other ways?
Is there some documentation for this feature out there?

In general I am little confused about scripting ways: What is the
difference between Python scripting/macro, Python programmable filter
and Python calculator? I guess scripting can do all of the other two
tools, too?

Regards Bastian