[basic.namespace.general]

# 9 Declarations [[dcl]](./#dcl)

## 9.9 Namespaces [[basic.namespace]](basic.namespace#general)

### 9.9.1 General [basic.namespace.general]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L8189)

A namespace is an optionally-named entity
whose scope can contain declarations of any kind of entity[.](#1.sentence-1)

The name of a
namespace can be used to access entities that belong to that namespace;
that is, the [*members*](#def:member,namespace "9.9.1 General [basic.namespace.general]") of the namespace[.](#1.sentence-2)

Unlike other entities,
the definition of a namespace can be split over several parts of one or
more translation units and modules[.](#1.sentence-3)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L8199)

[*Note [1](#note-1)*:

A [*namespace-definition*](namespace.def.general#nt:namespace-definition "9.9.2.1 General [namespace.def.general]") is exported
if it contains any[*export-declaration*](module.interface#nt:export-declaration "10.2 Export declaration [module.interface]")*s* ([[module.interface]](module.interface "10.2 Export declaration"))[.](#2.sentence-1)

A namespace is never attached to a named module
and never has a name with module linkage[.](#2.sentence-2)

— *end note*]

[*Example [1](#example-1)*: export module M;namespace N1 {} // N1 is not exportedexport namespace N2 {} // N2 is exportednamespace N3 { export int n; } // N3 is exported — *end example*]

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/declarations.tex#L8216)

There is a [*global namespace*](#def:namespace,global "9.9.1 General [basic.namespace.general]") with no declaration;
see [[basic.scope.namespace]](basic.scope.namespace "6.4.6 Namespace scope")[.](#3.sentence-1)

The global namespace belongs to the global scope;
it is not an unnamed namespace ([[namespace.unnamed]](namespace.unnamed "9.9.2.2 Unnamed namespaces"))[.](#3.sentence-2)

[*Note [2](#note-2)*:

Lacking a declaration, it cannot be found by name lookup[.](#3.sentence-3)

— *end note*]