What is the meaning of prepended double colon “::”?

Question

I found this line of a code in a class which I have to modify:

::Configuration * tmpCo = m_configurationDB;//pointer to current db

and I do

Answer 1

:: is a operator of defining the namespace.

For example, if you want to use cout without mentioning using namespace std; in your code you write this:

std::cout << "test";

When no namespace is mentioned, that it is said that class belongs to global namespace.