doc: add a few more updates

In particular, document the new behavior of EXTERN, GLOBAL and COMMON.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

doc/changes.src

@@ -11,12 +11,12 @@ since 2007.
 
 \b Fixed \c{subsections_via_symbols} for \c{macho} object format.
 
-\b Support to mangle labels based on the types through \c{%pragma}. See
-\k{mangling}.
-
 \b Added the \c{--gprefix}, \c{--gpostfix}, \c{--lprefix}, and
 \c{--lpostfix} command line options, to allow command line base symbol
-mangling. See \k{opt-pfix}.
+renaming. See \k{opt-pfix}.
+
+\b Allow label renaming to be specified by \c{%pragma} in addition to
+from the command line.  See \k{mangling}.
 
 \b Supported generic \c{%pragma} namespaces, \c{output} and \c{debug}. See
 \k{gen-namespace}.
@@ -34,6 +34,13 @@ Instruction) instructions.
 \b Added the \c{STATIC} directive for local symbols that should be
 renamed using global-symbol rules. See \k{static}.
 
+\b Allow a symbol to be defined as \c{EXTERN} and then later
+overridden as \c{GLOBAL} or \c{COMMON}. Furthermore, a symbol declared
+\c{EXTERN} and then defined will be treated as \c{GLOBAL}. See \k{extern}.
+
+\b The \c{GLOBAL} directive no longer is required to precede the
+definition of the symbol.
+
 \b Support \c{private_extern} as \c{macho} specific extension to the
 \c{GLOBAL} directive. See \k{macho-pext}.
 
@@ -42,14 +49,7 @@ renamed using global-symbol rules. See \k{static}.
 \b Added the \c{--limit-X} command line option to set execution
 limits. See \k{opt-limit}.
 
-\b Fixed \c{CPU} directive case insensitive
+\b Updated the \c{Codeview} version number to be aligned with \c{MASM}.
-
-\b Fixed modules name for \c{ELF}, \c{IEEE}, \c{macho}, \c{obj} output format
-
-\b Fixed to build \c{rdoff} tool and resolve to handle dependencies correctly
-with \c{Microsoft Visual Studio}
-
-\b Fixed \c{Codeview} version number to be aligned with \c{MASM}.
 
 \b Added the \c{--keep-all} command line option to preserve output
 files. See \k{opt-keep-all}.

doc/nasmdoc.src

@@ -4604,8 +4604,12 @@ only in that it can take only one argument at a time: the support
 for multiple arguments is implemented at the preprocessor level.
 
 You can declare the same variable as \c{EXTERN} more than once: NASM
-will quietly ignore the second and later redeclarations. You can't
+will quietly ignore the second and later redeclarations.
-declare a variable as \c{EXTERN} as well as something else, though.
+
+If a variable is declared both \c{GLOBAL} and \c{EXTERN}, or if it is
+declared as \c{EXTERN} and then defined, it will be treated as
+\c{GLOBAL}. If a variable is declared both as \c{COMMON} and
+\c{EXTERN}, it will be treated as \c{COMMON}.
 
 
 \H{global} \i\c{GLOBAL}: \i{Exporting Symbols} to Other Modules
@@ -4616,9 +4620,6 @@ linker errors, some other module must actually \e{define} the
 symbol and declare it as \c{GLOBAL}. Some assemblers use the name
 \i\c{PUBLIC} for this purpose.
 
-The \c{GLOBAL} directive applying to a symbol must appear \e{before}
-the definition of the symbol.
-
 \c{GLOBAL} uses the same syntax as \c{EXTERN}, except that it must
 refer to symbols which \e{are} defined in the same module as the
 \c{GLOBAL} directive. For example:
@@ -4673,11 +4674,10 @@ only one argument at a time.
 
 \H{static} \i\c{STATIC}: Local Symbols within Modules
 
-Opposite to \c{EXTERN} and \c{GLOBAL}, \c{STATIC} is local symbol,
+Opposite to \c{EXTERN} and \c{GLOBAL}, \c{STATIC} is local symbol, but
-but should be named according to the global mangling rules (named
+should be named according to the global mangling rules (named by
-by analogy with the C keyword "static" as applied to the functions).
+analogy with the C keyword \c{static} as applied to functions or
-And like \c{GLOBAL} directive, the directive applying to a symbol
+global variables).
-should be \i{before} the definition of the symbol. For example:
 
 \c static foo
 \c foo: