Annex C (informative) Compatibility [diff]

C.4 C++ and ISO C++ 2014 [diff.cpp14]

C.4.8 Clause [library]: library introduction [diff.cpp14.library]

[namespace.future]
Change: New reserved namespaces.
Rationale: Reserve namespaces for future revisions of the standard library that might otherwise be incompatible with existing programs.
Effect on original feature: The global namespaces std followed by an arbitrary sequence of digits is reserved for future standardization. Valid C++ 2014 code that uses such a top-level namespace, e.g., std2, may be invalid in this International Standard.