2 <clause number="16.3" title="Using directives">
3 <paragraph>Using-directives facilitate the use of namespaces and types defined in other namespaces. Using-directives impact the name resolution process of <non_terminal where="10.8">namespace-or-type-name</non_terminal>s (<hyperlink>10.8</hyperlink>) and <non_terminal where="14.5.2">simple-name</non_terminal>s (<hyperlink>14.5.2</hyperlink>), but unlike declarations, <non_terminal where="16.3">using-directive</non_terminal>s do not contribute new members to the underlying declaration spaces of the compilation units or namespaces within which they are used. <grammar_production><name><non_terminal where="16.3">using-directive</non_terminal>s</name> : <rhs><non_terminal where="16.3">using-directive</non_terminal></rhs><rhs><non_terminal where="16.3">using-directives</non_terminal><non_terminal where="16.3">using-directive</non_terminal></rhs></grammar_production><grammar_production><name><non_terminal where="16.3">using-directive</non_terminal></name> : <rhs><non_terminal where="16.3.1">using-alias-directive</non_terminal></rhs><rhs><non_terminal where="16.3.2">using-namespace-directive</non_terminal></rhs></grammar_production></paragraph>
4 <paragraph>A <non_terminal where="16.3.1">using-alias-directive</non_terminal> (<hyperlink>16.3.1</hyperlink>) introduces an alias for a namespace or type. </paragraph>
5 <paragraph>A <non_terminal where="16.3.2">using-namespace-directive</non_terminal> (<hyperlink>16.3.2</hyperlink>) imports the type members of a namespace. </paragraph>
6 <paragraph>The scope of a <non_terminal where="16.3">using-directive</non_terminal> extends over the <non_terminal where="16.4">namespace-member-declaration</non_terminal>s of its immediately containing compilation unit or namespace body. The scope of a <non_terminal where="16.3">using-directive</non_terminal> specifically does not include its peer <non_terminal where="16.3">using-directive</non_terminal>s. Thus, peer <non_terminal where="16.3">using-directive</non_terminal>s do not affect each other, and the order in which they are written is insignificant. </paragraph>