16
Library introduction
[library]
16.5
Library-wide requirements
[requirements]
16.5.4
Constraints on programs
[constraints]
16.5.4.2
Namespace use
[namespace.constraints]
16.5.4.2.3
Namespaces for future standardization
[namespace.future]
1
#
Top-level namespaces whose
namespace-name
consists of
std
followed by one or more
digit
s
are reserved for future standardization
.
The behavior of a C++ program is undefined if it adds declarations or definitions to such a namespace
.
[
Example
:
The top-level namespace
std2
is reserved for use by future revisions of this International Standard
.
—
end example
]