| __gnu_cxx | GNU extensions for public use |
| __gnu_cxx::__detail | Implementation details not part of the namespace __gnu_cxx interface |
| __gnu_cxx::typelist | GNU typelist extensions for public compile-time use |
| __gnu_debug | GNU debug classes for public use |
| __gnu_internal | GNU implemenation details, not for public use or export. Used only when anonymous namespaces cannot be substituted |
| __gnu_parallel | GNU parallel code for public use |
| __gnu_pbds | GNU extensions for policy-based data structures for public use |
| __gnu_profile | GNU profile code for public use |
| __gnu_sequential | GNU sequential classes for public use |
| abi | The cross-vendor C++ Application Binary Interface. A namespace alias to __cxxabiv1, but user programs should use the alias 'abi' |
| std | ISO C++ entities toplevel namespace is std |
| std::__debug | GNU debug code, replaces standard behavior with debug behavior |
| std::__detail | Implementation details not part of the namespace std interface |
| std::__parallel | GNU parallel code, replaces standard behavior with parallel behavior |
| std::__profile | GNU profile code, replaces standard behavior with profile behavior |
| std::chrono | ISO C++ 0x entities sub namespace for time and date |
| std::decimal | ISO/IEC TR 24733 Decimal floating-point arithmetic |
| std::placeholders | ISO C++ 0x entities sub namespace for functional.Define a large number of placeholders. There is no way to simplify this with variadic templates, because we're introducing unique names for each |
| std::regex_constants | ISO C++-0x entities sub namespace for regex |
| std::rel_ops | The generated relational operators are sequestered here |
| std::this_thread | ISO C++ 0x entities sub namespace for thread. 30.2.2 Namespace this_thread |
| std::tr1 | ISO C++ TR1 entities toplevel namespace is std::tr1 |
| std::tr1::__detail | Implementation details not part of the namespace std::tr1 interface |
