add missing mmap node

doc/standards.texi

@@ -1772,6 +1772,7 @@ when writing GNU software.
 * CPU Portability::             Supporting the range of CPU types
 * System Functions::            Portability and ``standard'' library functions
 * Internationalization::        Techniques for internationalization
+* Mmap::                        How you can safely use @code{mmap}.
 @end menu
 
 @node Formatting
@@ -1900,6 +1901,13 @@ page.  The formfeeds should appear alone on lines by themselves.
 Every program should start with a comment saying briefly what it is for.
 Example: @samp{fmt - filter for simple filling of text}.
 
+Please write the comments in a GNU program in English, because English
+is the one language that nearly all programmers in all countries can
+read.  If you do not write English well, please write comments in
+English as well as you can, then ask other people to help rewrite them.
+If you can't write comments in English, please find someone to work with
+you and translate your comments into English.
+
 Please put a comment on each function saying what the function does,
 what sorts of arguments it gets, and what the possible values of
 arguments mean and are used for.  It is not necessary to duplicate in
@@ -2100,6 +2108,15 @@ pointer constant, except when calling a varargs function.
 @node  Names
 @section Naming Variables and Functions
 
+The names of global variables and functions in a program serve as
+comments of a sort.  So don't choose terse names---instead, look for
+names that give useful information about the meaning of the variable or
+function.  In a GNU program, names should be English, like other
+comments.
+
+Local variable names can be shorter, because they are used only within
+one context, where (presumably) comments explain their purpose.
+
 Please use underscores to separate words in a name, so that the Emacs
 word commands can be useful within them.  Stick to lower case; reserve
 upper case for macros and @code{enum} constants, and for name-prefixes
@@ -2125,10 +2142,10 @@ When you want to define names with constant integer values, use
 constants.
 
 Use file names of 14 characters or less, to avoid creating gratuitous
-problems on older System V systems.  You can use the program @code{doschk} to test for
-this.  @code{doschk} also tests for potential name conflicts if the
-files were loaded onto an MS-DOS file system---something you may or may
-not care about.
+problems on older System V systems.  You can use the program
+@code{doschk} to test for this.  @code{doschk} also tests for potential
+name conflicts if the files were loaded onto an MS-DOS file
+system---something you may or may not care about.
 
 @node System Portability
 @section Portability between System Types
@@ -2236,6 +2253,25 @@ functions to avoid unnecessary loss of portability.
 Don't use the value of @code{sprintf}.  It returns the number of
 characters written on some systems, but not on all systems.
 
+@item
+Don't assume that @code{mmap} either works on all files or fails
+for all files.  It may work on some files and fail on others.
+
+The proper way to use @code{mmap} is to try it on the specific file for
+which you want to use it---and if @code{mmap} doesn't work, fall back on
+doing the job in another way using @code{read} and @code{write}.
+
+The reason this precaution is needed is that the GNU kernel (the HURD)
+provides a user-extensible file system, in which there can be many
+different kinds of ``ordinary files.''  Many of them support
+@code{mmap}, but some do not.  It is important to make programs handle
+all these kinds of files.
+
+@item
+@code{main} should be declared to return type @code{int}.  It should
+terminate either by calling @code{exit} or by returning the integer
+status code; make sure it cannot ever return an undefined value.
+
 @item
 Don't declare system functions explicitly.
 

standards.texi

@@ -1772,6 +1772,7 @@ when writing GNU software.
 * CPU Portability::             Supporting the range of CPU types
 * System Functions::            Portability and ``standard'' library functions
 * Internationalization::        Techniques for internationalization
+* Mmap::                        How you can safely use @code{mmap}.
 @end menu
 
 @node Formatting
@@ -1900,6 +1901,13 @@ page.  The formfeeds should appear alone on lines by themselves.
 Every program should start with a comment saying briefly what it is for.
 Example: @samp{fmt - filter for simple filling of text}.
 
+Please write the comments in a GNU program in English, because English
+is the one language that nearly all programmers in all countries can
+read.  If you do not write English well, please write comments in
+English as well as you can, then ask other people to help rewrite them.
+If you can't write comments in English, please find someone to work with
+you and translate your comments into English.
+
 Please put a comment on each function saying what the function does,
 what sorts of arguments it gets, and what the possible values of
 arguments mean and are used for.  It is not necessary to duplicate in
@@ -2100,6 +2108,15 @@ pointer constant, except when calling a varargs function.
 @node  Names
 @section Naming Variables and Functions
 
+The names of global variables and functions in a program serve as
+comments of a sort.  So don't choose terse names---instead, look for
+names that give useful information about the meaning of the variable or
+function.  In a GNU program, names should be English, like other
+comments.
+
+Local variable names can be shorter, because they are used only within
+one context, where (presumably) comments explain their purpose.
+
 Please use underscores to separate words in a name, so that the Emacs
 word commands can be useful within them.  Stick to lower case; reserve
 upper case for macros and @code{enum} constants, and for name-prefixes
@@ -2125,10 +2142,10 @@ When you want to define names with constant integer values, use
 constants.
 
 Use file names of 14 characters or less, to avoid creating gratuitous
-problems on older System V systems.  You can use the program @code{doschk} to test for
-this.  @code{doschk} also tests for potential name conflicts if the
-files were loaded onto an MS-DOS file system---something you may or may
-not care about.
+problems on older System V systems.  You can use the program
+@code{doschk} to test for this.  @code{doschk} also tests for potential
+name conflicts if the files were loaded onto an MS-DOS file
+system---something you may or may not care about.
 
 @node System Portability
 @section Portability between System Types
@@ -2236,6 +2253,25 @@ functions to avoid unnecessary loss of portability.
 Don't use the value of @code{sprintf}.  It returns the number of
 characters written on some systems, but not on all systems.
 
+@item
+Don't assume that @code{mmap} either works on all files or fails
+for all files.  It may work on some files and fail on others.
+
+The proper way to use @code{mmap} is to try it on the specific file for
+which you want to use it---and if @code{mmap} doesn't work, fall back on
+doing the job in another way using @code{read} and @code{write}.
+
+The reason this precaution is needed is that the GNU kernel (the HURD)
+provides a user-extensible file system, in which there can be many
+different kinds of ``ordinary files.''  Many of them support
+@code{mmap}, but some do not.  It is important to make programs handle
+all these kinds of files.
+
+@item
+@code{main} should be declared to return type @code{int}.  It should
+terminate either by calling @code{exit} or by returning the integer
+status code; make sure it cannot ever return an undefined value.
+
 @item
 Don't declare system functions explicitly.