[vtkusers] vtkStdString vs vtkstd::string

[David Doria]

The doc for vtkStdString says:

Wrapper around vtkstd::string to keep symbols short.
vtkStdString derives from vtkstd::string to provide shorter symbol
names than basic_string<...> in namespace std given by the standard
STL string.

But I guess I don't understand what that means. When should one use
vtkStdString vs vtkstd::string?

Thanks,

David