@@ -776,11 +776,7 @@
 \pnum
 \indextext{scope!namespace}%
 The declarative region of a \grammarterm{namespace-definition} is its
-\grammarterm{namespace-body}. The potential scope denoted by an
-\grammarterm{original-namespace-name} is the concatenation of the
-declarative regions established by each of the
-\grammarterm{namespace-definition}{s} in the same declarative region with
-that \grammarterm{original-namespace-name}. Entities declared in a
+\grammarterm{namespace-body}.  Entities declared in a
 \grammarterm{namespace-body} are said to be \defn{members} of the
 namespace, and names introduced by these declarations into the
 declarative region of the namespace are said to be \defn{member
 
@@ -2092,15 +2092,10 @@
 
 \begin{bnf}
 \nontermdef{namespace-name}\br
-        original-namespace-name\br
+        identifier\br
         namespace-alias
 \end{bnf}
 
-\begin{bnf}
-\nontermdef{original-namespace-name}\br
-        identifier
-\end{bnf}
-
 \begin{bnf}
 \nontermdef{namespace-definition}\br
         named-namespace-definition\br
@@ -2109,20 +2104,9 @@
 
 \begin{bnf}
 \nontermdef{named-namespace-definition}\br
-        original-namespace-definition\br
-        extension-namespace-definition
-\end{bnf}
-
-\begin{bnf}
-\nontermdef{original-namespace-definition}\br
         \terminal{inline\opt} \terminal{namespace} identifier \terminal{\{} namespace-body \terminal{\}}
 \end{bnf}
 
-\begin{bnf}
-\nontermdef{extension-namespace-definition}\br
-        \terminal{inline\opt} \terminal{namespace} original-namespace-name \terminal{\{} namespace-body \terminal{\}}
-\end{bnf}
-
 \begin{bnf}
 \nontermdef{unnamed-namespace-definition}\br
         \terminal{inline\opt} \terminal{namespace \{} namespace-body \terminal{\}}
@@ -2133,24 +2117,24 @@
         declaration-seq\opt
 \end{bnf}
 
-\pnum
-The \grammarterm{identifier} in an \grammarterm{original-namespace-definition}
-shall not have been previously defined in the declarative region in
-which the \grammarterm{original-namespace-definition} appears. The
-\grammarterm{identifier} in an \grammarterm{original-namespace-definition} is
-the name of the namespace. Subsequently in that declarative region, it
-is treated as an \grammarterm{original-namespace-name}.
-
-\pnum
-The \grammarterm{original-namespace-name} in an
-\grammarterm{extension-namespace-definition} shall have previously been
-defined in an \grammarterm{original-namespace-definition} in the same
-declarative region.
-
 \pnum
 Every \grammarterm{namespace-definition} shall appear in the global scope
 or in a namespace scope~(\ref{basic.scope.namespace}).
 
+\pnum
+In a \grammarterm{named-namespace-definition},
+the \grammarterm{identifier} is the name of the namespace.
+If the \grammarterm{identifier}, when looked up~(\ref{basic.lookup.unqual}),
+refers to a \grammarterm{namespace-name} (but not a \grammarterm{namespace-alias})
+introduced in the declarative region
+in which the \grammarterm{named-namespace-definition} appears,
+the \grammarterm{namespace-definition}
+\indextext{extend|see{namespace, extend}}
+\defnx{extends}{namespace!extend} the previously-declared namespace.
+Otherwise, the \grammarterm{identifier} is introduced
+as a \grammarterm{namespace-name} into the declarative region
+in which the \grammarterm{named-namespace-definition} appears.
+
 \pnum
 Because a \grammarterm{namespace-definition} contains
 \grammarterm{declaration}{s} in its \grammarterm{namespace-body} and a
@@ -2197,9 +2181,9 @@
 If the optional initial \tcode{inline} keyword appears in a
 \grammarterm{namespace-definition} for a particular namespace, that namespace is
 declared to be an \term{inline namespace}. The \tcode{inline} keyword may be
-used on an \grammarterm{extension-namespace-definition} only if it was
-previously used on the \grammarterm{original-namespace-definition} for that
-namespace.
+used on a \grammarterm{namespace-definition} that extends a namespace
+only if it was previously used on the \grammarterm{namespace-definition} 
+that initially declared the \grammarterm{namespace-name} for that namespace.
 
 \pnum
 Members of an inline namespace can be used in most respects as though they were members
@@ -2424,14 +2408,6 @@
 \end{codeblock}
 \exitexample
 
-\pnum
-A \grammarterm{namespace-name} or \grammarterm{namespace-alias} shall not be
-declared as the name of any other entity in the same declarative region.
-A \grammarterm{namespace-name} defined at global scope shall not be
-declared as the name of any other entity in any global scope of the
-program. No diagnostic is required for a violation of this rule by
-declarations in different translation units.
-
 \rSec2[namespace.udecl]{The \tcode{using} declaration}%
 \indextext{using-declaration|(}
 
@@ -2976,14 +2952,14 @@
 \end{codeblock}
 \exitexample
 
+
 \pnum
-If a namespace is extended by an
-\grammarterm{extension-namespace-definition} after a
+If a namespace is extended~(\ref{namespace.def}) after a
 \grammarterm{using-directive} for that namespace is given, the additional
 members of the extended namespace and the members of namespaces
 nominated by \grammarterm{using-directive}{s} in the
-\grammarterm{extension-namespace-definition} can be used after the
-\grammarterm{extension-namespace-definition}.
+extending \grammarterm{namespace-definition} can be used after the
+extending \grammarterm{namespace-definition}.
 
 \pnum
 If name lookup finds a declaration for a name in two different