The root of the entire intermediate representation is the variable
global_namespace. This is the namespace specified with ::
in C++ source code. All other namespaces, types, variables, functions,
and so forth can be found starting with this namespace.
Besides namespaces, the other high-level scoping construct in C++ is the
class. (Throughout this manual the term class is used to mean the
types referred to in the ANSI/ISO C++ Standard as classes; these include
types defined with the class, struct, and union
keywords.)