START-INFO-DIR-ENTRY
* libidn:	(libidn)Internationalized string processing library.
END-INFO-DIR-ENTRY


...Table of Contents...
GNU Libidn
**********

This manual is for GNU Libidn (version 0.1.3, 15 January 2003), which
is a library for internationalized string processing.

   Copyright (C) 2002 Free Software Foundation, Inc.

     Permission is granted to copy, distribute and/or modify this
     document under the terms of the GNU Free Documentation License,
     Version 1.1 or any later version published by the Free Software
     Foundation; with no Invariant Sections, with the Front-Cover Texts
     being "A GNU Manual," and with the Back-Cover Texts as in (a)
     below.  A copy of the license is included in the section entitled
     "GNU Free Documentation License."

     (a) The FSF's Back-Cover Text is: "You have freedom to copy and
     modify this GNU Manual, like GNU software.  Copies published by
     the Free Software Foundation raise funds for GNU development."
   
Introduction
************

   GNU Libidn is an implementation of the Stringprep (with the Nameprep
and Kerberos 5 profiles), Punycode and IDNA specifications defined by
the IETF Internationalized Domain Names (IDN) working group, used for
internationalized domain names.  It is licensed under the GNU Lesser
General Public License.

   The library contains a generic Stringprep implementation (including
Unicode 3.2 NFKC normalization, table mapping of characters, and
Bidirectional Character handling), two Stringprep profiles; Nameprep
(for IDN) and Kerberos5, as well as a Punycode and IDNA.

   The Stringprep API consists of two main functions, one for converting
data from the system's native representation into UTF-8, and one
function to perform the Stringprep processing.  Each stringprep profile
has a corresponding CPP macro.  Adding a new Stringprep profile for
your application within the API is straightforward.  The Punycode API
consists of one encoding function and one decoding function.  The IDNA
API consists of the ToASCII and ToUnicode functions.

   The library is currently used by forthcoming SASL and Kerberos
libraries to process user names and passwords before they are input to
cryptographic operations.  It is also used by experimental code for
domain name related purposes.

   GNU Libidn is developed for the GNU/Linux system, but runs on over 20
Unix platforms (including Solaris, IRIX, AIX, and Tru64) and Windows.

Getting Started
===============

   This manual documents the library programming interface.  All
functions and data types provided by the library are explained.

   The reader is assumed to possess basic familiarity with
internationalization concepts and network programming in C or C++.

   This manual can be used in several ways.  If read from the beginning
to the end, it gives a good introduction into the library and how it
can be used in an application.  Forward references are included where
necessary.  Later on, the manual can be used as a reference manual to
get just the information needed about any particular interface of the
library.  Experienced programmers might want to start looking at the
examples at the end of the manual (*note Examples::), and then only
read up those parts of the interface which are unclear.

Features
========

   This library might have a couple of advantages over other libraries
doing a similar job.

It's Free Software
     Anybody can use, modify, and redistribute it under the terms of the
     GNU Lesser General Public License.

It's thread-safe
     No global state is kept in the library.

It's portable
     It should work on all Unix like operating systems, including
     Windows.

Supported Platforms
===================

   Libidn has at some point in time been tested on the following
platforms.

  1. Debian GNU/Linux 3.0r0 (Woody)

     GCC 2.95.4 and GNU Make. This is the main development platform.
     alphaev67-unknown-linux-gnu, alphaev6-unknown-linux-gnu,
     hppa64-unknown-linux-gnu, i686-pc-linux-gnu,
     ia64-unknown-linux-gnu.

  2. Tru64 UNIX

     Tru64 UNIX C compiler and Tru64 Make. alphaev68-dec-osf5.1.

  3. SuSE Linux 7.1

     GCC 2.96 and GNU Make. alphaev67-unknown-linux-gnu.

  4. SuSE Linux 7.2a

     GCC 3.0 and GNU Make. ia64-unknown-linux-gnu.

  5. RedHat Linux 7.2

     GCC 2.96 and GNU Make. i686-pc-linux-gnu.

  6. RedHat Linux 8.0

     GCC 3.2 and GNU Make. i686-pc-linux-gnu.

  7. IRIX 6.5

     mips-sgi-irix6.5, MIPS C compiler, IRIX Make.

  8. AIX 4.3.2

     rs6000-ibm-aix4.3.2.0, IBM C for AIX compiler, AIX Make.

  9. Microsoft Windows 2000 (Cygwin)

     GCC 3.2, GNU make. i686-pc-cygwin

 10. HP-UX 11.11

     HP-UX C compiler and HP Make. hppa2.0w-hp-hpux11.11.

 11. SUN Solaris 2.8

     Sun WorkShop Compiler C 6.0 and SUN Make. sparc-sun-solaris2.8.

 12. NetBSD 1.6

     GCC 2.95.3 and GNU Make. alpha-unknown-netbsd1.6,
     i386-unknown-netbsdelf1.6.

 13. OpenBSD 3.1

     GCC 2.95.3 and GNU Make.  i386-unknown-openbsd3.1.

 14. FreeBSD 4.7

     GCC 2.95.4 and GNU Make. alpha-unknown-freebsd4.7,
     i386-unknown-freebsd4.7.


   If you use Libidn on, or port Libidn to, a new platform please report
it to the author.

Bug Reports
===========

   If you think you have found a bug in Libidn, please investigate it
and report it.

   * Please make sure that the bug is really in Libidn, and preferably
     also check that it hasn't already been fixed in the latest version.

   * You have to send us a test case that makes it possible for us to
     reproduce the bug.

   * You also have to explain what is wrong; if you get a crash, or if
     the results printed are not good and in that case, in what way.
     Make sure that the bug report includes all information you would
     need to fix this kind of bug for someone else.


   Please make an effort to produce a self-contained report, with
something definite that can be tested or debugged.  Vague queries or
piecemeal messages are difficult to act on and don't help the
development effort.

   If your bug report is good, we will do our best to help you to get a
corrected version of the software; if the bug report is poor, we won't
do anything about it (apart from asking you to send better bug reports).

   If you think something in this manual is unclear, or downright
incorrect, or if the language needs to be improved, please also send a
note.

   Send your bug report to:

                         `bug-libidn@gnu.org'

Preparation
***********

   To use `Libidn, you have to perform some changes to your sources and
the build system.  The necessary changes are small and explained in the
following sections.  At the end of this chapter, it is described how
the library is initialized, and how the requirements of the library are
verified.

   A faster way to find out how to adapt your application for use with
`Libidn' may be to look at the examples at the end of this manual
(*note Examples::).

Header
======

   The library contains a few independent parts, and each part export
the interfaces (data types and functions) in a header file.  You must
include the appropriate header files in all programs using the library,
either directly or through some other header file, like this:

     #include <stringprep.h>

   The header files and the functions they define are categorized as
follows:

stringprep.h
     The low-level stringprep API entry point.  Normal applications uses
     one specific stringprep profile, and should rather include the
     corresponding profile header file (see below).  If you are writing
     an application that only makes use of the utility functions,
     including this header file may be more appropriate however.

     The name space of the stringprep part of Libidn is `stringprep_*'
     for function names, `Stringprep*' for data types and
     `STRINGPREP_*' for other symbols.  In addition the same name
     prefixes with one prepended underscore are reserved for internal
     use and should never be used by an application.

stringprep_generic.h
     The entry point to the generic tables specified in the stringprep
     specification.  It is normally only needed by applications that
     want to define its own stringprep profile, based on the generic
     tables.

     This header file uses the same namespace as the main stringprep.h
     header file.

stringprep_nameprep.h
     The entry point to the nameprep profile of stringprep.  This is the
     entry point used by applications needing low-level access to the
     stringprep profile used in IDN.  Most applications requesting IDN
     functionality will want idna.h instead though.

     This header file uses the same namespace as the main stringprep.h
     header file.

stringprep_kerberos5.h
     The entry point to the experimental Kerberos 5 profile of
     stringprep.

     This header file uses the same namespace as the main stringprep.h
     header file.

punycode.h
     The entry point to Punycode encoding and decoding functions.
     Normally punycode is used via the idna.h interface, but some
     application may want to perform raw punycode operations.

     The name space of the punycode part of Libidn is `punycode_*' for
     function names, `Punycode*' for data types and `PUNYCODE_*' for
     other symbols.  In addition the same name prefixes with one
     prepended underscore are reserved for internal use and should
     never be used by an application.

idna.h
     The entry point to the IDNA functions.  This is the normal entry
     point for applications that need IDN functionality.

     The name space of the IDNA part of Libidn is `idna_*' for function
     names, `Idna*' for data types and `IDNA_*' for other symbols.  In
     addition the same name prefixes with one prepended underscore are
     reserved for internal use and should never be used by an
     application.

Initialization
==============

   Libidn is stateless and does not need any initialization.

Version Check
=============

   It is often desirable to check that the version of `Libidn' used is
indeed one which fits all requirements.  Even with binary compatibility
new features may have been introduced but due to problem with the
dynamic linker an old version is actually used.  So you may want to
check that the version is okay right after program startup.

 - Function: const char * stringprep_check_version (const char *
          REQ_VERSION)
     REQ_VERSION:  Required version number, or NULL.

     Check that the the version of the library is at minimum the
     requested one and return the version string; return NULL if the
     condition is not satisfied.  If a NULL is passed to this function,
     no check is done, but the version string is simply returned.

     See STRINGPREP_VERSION for a suitable `req_version' string.

     Version string of run-time library, or NULL if the run-time
     library does not meet the required version number.


   The normal way to use the function is to put something similar to the
following first in your `main()':

       if (!stringprep_check_version (STRINGPREP_VERSION))
         {
           printf ("stringprep_check_version() failed:\n"
                   "Header file incompatible with shared library.\n");
           exit(1);
         }

Building the source
===================

   If you want to compile a source file including e.g. the `idna.h'
header file, you must make sure that the compiler can find it in the
directory hierarchy.  This is accomplished by adding the path to the
directory in which the header file is located to the compilers include
file search path (via the `-I' option).

   However, the path to the include file is determined at the time the
source is configured.  To solve this problem, `Libidn' uses the
external package `pkg-config' that knows the path to the include file
and other configuration options.  The options that need to be added to
the compiler invocation at compile time are output by the `--cflags'
option to `pkg-config libidn'.  The following example shows how it can
be used at the command line:

     gcc -c foo.c `pkg-config libidn --cflags`

   Adding the output of `pkg-config libidn --cflags' to the compilers
command line will ensure that the compiler can find e.g. the idna.h
header file.

   A similar problem occurs when linking the program with the library.
Again, the compiler has to find the library files.  For this to work,
the path to the library files has to be added to the library search
path (via the `-L' option).  For this, the option `--libs' to
`pkg-config libidn' can be used.  For convenience, this option also
outputs all other options that are required to link the program with
the `libidn' libarary.  The example shows how to link `foo.o' with the
`libidn' library to a program `foo'.

     gcc -o foo foo.o `pkg-config libidn --libs`

   Of course you can also combine both examples to a single command by
specifying both options to `pkg-config':

     gcc -o foo foo.c `pkg-config libidn --cflags --libs`

Stringprep Functions
********************

   Stringprep describes a framework for preparing Unicode text strings
in order to increase the likelihood that string input and string
comparison work in ways that make sense for typical users throughout
the world. The stringprep protocol is useful for protocol identifier
values, company and personal names, internationalized domain names, and
other text strings.

 - Function: int stringprep (char * IN, int MAXLEN, int FLAGS,
          Stringprep_profile * PROFILE)
     IN:  input/ouput array with string to prepare.

     MAXLEN:  maximum length of input/output array.

     FLAGS:  optional stringprep profile flags.

     PROFILE:  pointer to stringprep profile to use.

     Prepare the input UTF-8 string according to the stringprep profile.
     Normally application programmers use stringprep profile macros such
     as `stringprep_nameprep()', `stringprep_kerberos5()' etc instead of
     calling this function directly.

     Returns 0 iff successful, or an error code.


 - Function: unsigned long stringprep_utf8_to_unichar (const char * P)
     P:  a pointer to Unicode character encoded as UTF-8

     Converts a sequence of bytes encoded as UTF-8 to a Unicode
     character.  If `p' does not point to a valid UTF-8 encoded
     character, results are undefined.

     the resulting character


 - Function: int stringprep_unichar_to_utf8 (unsigned long C, char *
          OUTBUF)
     C:  a ISO10646 character code

     OUTBUF:  output buffer, must have at least 6 bytes of space.  If
     NULL, the length will be computed and returned and nothing will be
     written to `outbuf'.

     Converts a single character to UTF-8.

     number of bytes written


 - Function: unsigned long * stringprep_utf8_to_ucs4 (const char * STR,
          int LEN, int * ITEMS_WRITTEN)
     STR:  a UTF-8 encoded string

     LEN:  the maximum length of `str' to use. If `len' < 0, then the
     string is nul-terminated.

     ITEMS_WRITTEN:  location to store the number of characters in the
     result, or NULL.

     Convert a string from UTF-8 to a 32-bit fixed width representation
     as UCS-4, assuming valid UTF-8 input.  This function does no error
     checking on the input.

     a pointer to a newly allocated UCS-4 string.  This value must be
     freed with `free()'.


 - Function: char * stringprep_ucs4_to_utf8 (const unsigned long * STR,
          int LEN, int * ITEMS_READ, int * ITEMS_WRITTEN)
     STR:  a UCS-4 encoded string

     LEN:  the maximum length of `str' to use. If `len' < 0, then the
     string is terminated with a 0 character.

     ITEMS_READ:  location to store number of characters read read, or
     NULL.

     ITEMS_WRITTEN:  location to store number of bytes written or NULL.
     The value here stored does not include the trailing 0 byte.

     Convert a string from a 32-bit fixed width representation as UCS-4.
     to UTF-8. The result will be terminated with a 0 byte.

     a pointer to a newly allocated UTF-8 string.  This value must be
     freed with `free()'. If an error occurs, NULL will be returned and
     `error' set.


 - Function: char * stringprep_utf8_nfkc_normalize (const char * STR,
          int LEN)
     STR:  a UTF-8 encoded string.

     LEN:  length of `str', in bytes, or -1 if `str' is nul-terminated.

     Converts a string into canonical form, standardizing such issues
     as whether a character with an accent is represented as a base
     character and combining accent or as a single precomposed
     character. You should generally call `g_utf8_normalize()' before
     comparing two Unicode strings.

     The normalization mode is NFKC (ALL COMPOSE).  It standardizes
     differences that do not affect the text content, such as the
     above-mentioned accent representation. It standardizes the
     "compatibility" characters in Unicode, such as SUPERSCRIPT THREE to
     the standard forms (in this case DIGIT THREE). Formatting
     information may be lost but for most text operations such
     characters should be considered the same. It returns a result with
     composed forms rather than a maximally decomposed form.

     a newly allocated string, that is the NFKC normalized form of
     `str'.


 - Function: unsigned long * stringprep_ucs4_nfkc_normalize (unsigned
          long * STR, int LEN)
     STR:  a Unicode string.

     LEN:  length of `str' array, or -1 if `str' is nul-terminated.

     Converts UCS4 string into UTF-8 and runs
     `stringprep_utf4_nfkc_normalize()'.

     a newly allocated Unicode string, that is the NFKC normalized form
     of `str'.


 - Function: const char * stringprep_locale_charset ( VOID)
     Return the character set used by the system locale.  It will never
     return NULL, but use "ASCII" as a fallback.


 - Function: char * stringprep_convert (const char * STR, const char *
          TO_CODESET, const char * FROM_CODESET)
     STR:  input zero-terminated string.

     TO_CODESET:  name of destination character set.

     FROM_CODESET:  name of origin character set, as used by `str'.

     Convert the string from one character set to another using the
     system's `iconv()' function.

     Returns newly allocated zero-terminated string which is `str'
     transcoded into to_codeset.


 - Function: char * stringprep_locale_to_utf8 (const char * STR)
     STR:  input zero terminated string.

     Convert string encoded in the locale's character set into UTF-8 by
     using `stringprep_convert()'.

     Returns newly allocated zero-terminated string which is `str'
     transcoded into UTF-8.


 - Function: char * stringprep_utf8_to_locale (const char * STR)
     STR:  input zero terminated string.

     Convert string encoded in UTF-8 into the locale's character set by
     using `stringprep_convert()'.

     Returns newly allocated zero-terminated string which is `str'
     transcoded into the locale's character set.


Punycode Functions
******************

   Punycode is a simple and efficient transfer encoding syntax designed
for use with Internationalized Domain Names in Applications. It
uniquely and reversibly transforms a Unicode string into an ASCII
string. ASCII characters in the Unicode string are represented
literally, and non-ASCII characters are represented by ASCII characters
that are allowed in host name labels (letters, digits, and hyphens).
This document defines a general algorithm called Bootstring that allows
a string of basic code points to uniquely represent any string of code
points drawn from a larger set. Punycode is an instance of Bootstring
that uses particular parameter values specified by this document,
appropriate for IDNA.

 - Function: int punycode_encode (size_t INPUT_LENGTH, const unsigned
          long INPUT[], const unsigned char CASE_FLAGS[], size_t *
          OUTPUT_LENGTH, char OUTPUT[])
     INPUT_LENGTH:  The input_length is the number of code points in
     the input.

     OUTPUT_LENGTH:  The output_length is an in/out argument: the caller
     passes in the maximum number of code points that it can receive,
     and on successful return it will contain the number of code points
     actually output.

     Converts Unicode to Punycode.

     The return value can be any of the punycode_status values defined
     above except punycode_bad_input; if not punycode_success, then
     output_size and output might contain garbage.


 - Function: int punycode_decode (size_t INPUT_LENGTH, const char
          INPUT[], size_t * OUTPUT_LENGTH, unsigned long OUTPUT[],
          unsigned char CASE_FLAGS[])
     INPUT_LENGTH:  The input_length is the number of code points in
     the input.

     OUTPUT_LENGTH:  The output_length is an in/out argument: the caller
     passes in the maximum number of code points that it can receive,
     and on successful return it will contain the actual number of code
     points output.

     Converts Punycode to Unicode.

     The return value can be any of the punycode_status values defined
     above; if not punycode_success, then output_length, output, and
     case_flags might contain garbage.  On success, the decoder will
     never need to write an output_length greater than input_length,
     because of how the encoding is defined.


IDNA Functions
**************

   Until now, there has been no standard method for domain names to use
characters outside the ASCII repertoire. The IDNA document defines
internationalized domain names (IDNs) and a mechanism called IDNA for
handling them in a standard fashion. IDNs use characters drawn from a
large repertoire (Unicode), but IDNA allows the non-ASCII characters to
be represented using only the ASCII characters already allowed in
so-called host names today. This backward-compatible representation is
required in existing protocols like DNS, so that IDNs can be introduced
with no changes to the existing infrastructure. IDNA is only meant for
processing domain names, not free text.

 - Function: int idna_to_ascii (const unsigned long * IN, size_t INLEN,
          char * OUT, int ALLOWUNASSIGNED, int USESTD3ASCIIRULES)
     IN:  input array with unicode code points.

     INLEN:  length of input array with unicode code points.

     OUT:  output zero terminated string that must have room for at
     least 63 characters plus the terminating zero.

     ALLOWUNASSIGNED:  boolean value as per IDNA specification.

     USESTD3ASCIIRULES:  boolean value as per IDNA specification.

     The ToASCII operation takes a sequence of Unicode code points that
     make up one label and transforms it into a sequence of code points
     in the ASCII range (0..7F). If ToASCII succeeds, the original
     sequence and the resulting sequence are equivalent labels.

     It is important to note that the ToASCII operation can fail.
     ToASCII fails if any step of it fails. If any step of the ToASCII
     operation fails on any label in a domain name, that domain name
     MUST NOT be used as an internationalized domain name. The method
     for deadling with this failure is application-specific.

     The inputs to ToASCII are a sequence of code points, the
     AllowUnassigned flag, and the UseSTD3ASCIIRules flag. The output
     of ToASCII is either a sequence of ASCII code points or a failure
     condition.

     ToASCII never alters a sequence of code points that are all in the
     ASCII range to begin with (although it could fail). Applying the
     ToASCII operation multiple times has exactly the same effect as
     applying it just once.

     Returns 0 on success, or an error code.


 - Function: int idna_to_unicode (const unsigned long * IN, size_t
          INLEN, unsigned long * OUT, size_t * OUTLEN, int
          ALLOWUNASSIGNED, int USESTD3ASCIIRULES)
     IN:  input array with unicode code points.

     INLEN:  length of input array with unicode code points.

     OUT:  output array with unicode code points.

     OUTLEN:  on input, maximum size of output array with unicode code
     points, on exit, actual size of output array with unicode code
     points.

     ALLOWUNASSIGNED:  boolean value as per IDNA specification.

     USESTD3ASCIIRULES:  boolean value as per IDNA specification.

     The ToUnicode operation takes a sequence of Unicode code points
     that make up one label and returns a sequence of Unicode code
     points. If the input sequence is a label in ACE form, then the
     result is an equivalent internationalized label that is not in ACE
     form, otherwise the original sequence is returned unaltered.

     ToUnicode never fails. If any step fails, then the original input
     sequence is returned immediately in that step.

     The ToUnicode output never contains more code points than its
     input.  Note that the number of octets needed to represent a
     sequence of code points depends on the particular character
     encoding used.

     The inputs to ToUnicode are a sequence of code points, the
     AllowUnassigned flag, and the UseSTD3ASCIIRules flag. The output of
     ToUnicode is always a sequence of Unicode code points.

     Returns error condition, but it must only be used for debugging
     purposes.  The output buffer is always guaranteed to contain the
     correct data according to the specification (sans malloc induced
     errors).  NB!  This means that you normally ignore the return code
     from this function, as checking it means breaking the standard.


 - Function: int idna_ucs4_to_ace (const unsigned long * INPUT, char **
          OUTPUT)
     INPUT:  zero terminated input Unicode string.

     OUTPUT:  pointer to newly allocated output string.

     Convert UCS-4 domain name to ASCII string.  The AllowUnassigned
     flag is false and std3asciirules flag is false.  The domain name
     may contain several labels, separated by dots.  The output buffer
     must be deallocated by the caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_utf8_to_ace (const char * INPUT, char ** OUTPUT)
     INPUT:  zero terminated input UTF-8 string.

     OUTPUT:  pointer to newly allocated output string.

     Convert UTF-8 domain name to ASCII string.  The AllowUnassigned
     flag is false and std3asciirules flag is false.  The domain name
     may contain several labels, separated by dots.  The output buffer
     must be deallocated by the caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_locale_to_ace (const char * INPUT, char ** OUTPUT)
     INPUT:  zero terminated input UTF-8 string.

     OUTPUT:  pointer to newly allocated output string.

     Convert domain name in the locale's encoding to ASCII string.  The
     AllowUnassigned flag is false and std3asciirules flag is false.
     The domain name may contain several labels, separated by dots.  The
     output buffer must be deallocated by the caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_ucs4ace_to_ucs4 (const unsigned long * INPUT,
          unsigned long ** OUTPUT)
     INPUT:  zero-terminated Unicode string.

     OUTPUT:  pointer to newly allocated output Unicode string.

     Convert possibly ACE encoded domain name in UCS-4 format into a
     UCS-4 string.  The AllowUnassigned flag is false and std3asciirules
     flag is false.  The domain name may contain several labels,
     separated by dots.  The output buffer must be deallocated by the
     caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_utf8ace_to_ucs4 (const char * INPUT, unsigned
          long ** OUTPUT)
     INPUT:  zero-terminated UTF-8 string.

     OUTPUT:  pointer to newly allocated output Unicode string.

     Convert possibly ACE encoded domain name in UTF-8 format into a
     UCS-4 string.  The AllowUnassigned flag is false and std3asciirules
     flag is false.  The domain name may contain several labels,
     separated by dots.  The output buffer must be deallocated by the
     caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_utf8ace_to_utf8 (const char * INPUT, char **
          OUTPUT)
     INPUT:  zero-terminated UTF-8 string.

     OUTPUT:  pointer to newly allocated output UTF-8 string.

     Convert possibly ACE encoded domain name in UTF-8 format into a
     UTF-8 string.  The AllowUnassigned flag is false and std3asciirules
     flag is false.  The domain name may contain several labels,
     separated by dots.  The output buffer must be deallocated by the
     caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_utf8ace_to_locale (const char * INPUT, char **
          OUTPUT)
     INPUT:  zero-terminated UTF-8 string.

     OUTPUT:  pointer to newly allocated output string encoded in the
     current locale's character set.

     Convert possibly ACE encoded domain name in UTF-8 format into a
     string encoded in the current locale's character set.  The
     AllowUnassigned flag is false and std3asciirules flag is false.
     The domain name may contain several labels, separated by dots.  The
     output buffer must be deallocated by the caller.

     Returns IDNA_SUCCESS on success, or error code.


 - Function: int idna_localeace_to_locale (const char * INPUT, char **
          OUTPUT)
     INPUT:  zero-terminated string encoded in the current locale's
     character set.

     OUTPUT:  pointer to newly allocated output string encoded in the
     current locale's character set.

     Convert possibly ACE encoded domain name in the locale's character
     set into a string encoded in the current locale's character set.
     The AllowUnassigned flag is false and std3asciirules flag is false.
     The domain name may contain several labels, separated by dots.  The
     output buffer must be deallocated by the caller.

     Returns IDNA_SUCCESS on success, or error code.


Examples
********

   This chapter contains example code which illustrate how `Libidn' can
be used when writing your own application.

Example 1
=========

   This example demonstrates how the stringprep functions are used.

     /* example.c	Example code showing how to use stringprep().
      * Copyright (C) 2002  Simon Josefsson
      *
      * This file is part of Libstringprep.
      *
      * Libstringprep is free software; you can redistribute it and/or
      * modify it under the terms of the GNU Lesser General Public
      * License as published by the Free Software Foundation; either
      * version 2.1 of the License, or (at your option) any later version.
      *
      * Libstringprep is distributed in the hope that it will be useful,
      * but WITHOUT ANY WARRANTY; without even the implied warranty of
      * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      * Lesser General Public License for more details.
      *
      * You should have received a copy of the GNU Lesser General Public
      * License along with Libstringprep; if not, write to the Free Software
      * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      *
      */
     
     #include <stdio.h>
     #include <stdlib.h>
     #include <string.h>
     #include <stringprep_nameprep.h>
     
     /*
      * Compiling using libtool and pkg-config is recommended:
      *
      * $ libtool cc -o example example.c `pkg-config --cflags --libs libstringprep`
      * $ ./example
      * Input string encoded as `ISO-8859-1': 
      * Before locale2utf8 (length 2): aa 0a
      * Before stringprep (length 3): c2 aa 0a
      * After stringprep (length 2): 61 0a
      * $
      *
      */
     
     int
     main (int argc, char *argv[])
     {
       char buf[BUFSIZ];
       char *p;
       int rc, i;
     
       printf ("Input string encoded as `%s': ", stringprep_locale_charset ());
       fflush (stdout);
       fgets (buf, BUFSIZ, stdin);
     
       printf ("Before locale2utf8 (length %d): ", strlen (buf));
       for (i = 0; i < strlen (buf); i++)
         printf ("%02x ", buf[i] & 0xFF);
       printf ("\n");
     
       p = stringprep_locale_to_utf8 (buf);
       if (p)
         {
           strcpy (buf, p);
           free (p);
         }
       else
         printf ("Could not convert string to UTF-8, continuing anyway...\n");
     
       printf ("Before stringprep (length %d): ", strlen (buf));
       for (i = 0; i < strlen (buf); i++)
         printf ("%02x ", buf[i] & 0xFF);
       printf ("\n");
     
       rc = stringprep (buf, BUFSIZ, 0, stringprep_nameprep);
       if (rc != STRINGPREP_OK)
         printf ("Stringprep failed with rc %d...\n", rc);
       else
         {
           printf ("After stringprep (length %d): ", strlen (buf));
           for (i = 0; i < strlen (buf); i++)
     	printf ("%02x ", buf[i] & 0xFF);
           printf ("\n");
         }
     
       return 0;
     }

Example 2
=========

   This example demonstrates how the punycode functions are used.

     /* example2.c	Example code showing how to use punycode.
      * Copyright (C) 2002  Adam M. Costello
      * Copyright (C) 2002  Simon Josefsson
      *
      * This file is part of Libstringprep.
      *
      * Libstringprep is free software; you can redistribute it and/or
      * modify it under the terms of the GNU Lesser General Public
      * License as published by the Free Software Foundation; either
      * version 2.1 of the License, or (at your option) any later version.
      *
      * Libstringprep is distributed in the hope that it will be useful,
      * but WITHOUT ANY WARRANTY; without even the implied warranty of
      * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      * Lesser General Public License for more details.
      *
      * You should have received a copy of the GNU Lesser General Public
      * License along with Libstringprep; if not, write to the Free Software
      * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      *
      */
     
     /*
      * This file is derived from from draft-ietf-idn-punycode-03.txt by
      * Adam M. Costello.
      *
      * Disclaimer and license: Regarding this entire document or any
      * portion of it (including the pseudocode and C code), the author
      * makes no guarantees and is not responsible for any damage resulting
      * from its use.  The author grants irrevocable permission to anyone
      * to use, modify, and distribute it in any way that does not diminish
      * the rights of anyone else to use, modify, and distribute it,
      * provided that redistributed derivative works do not contain
      * misleading author or version information.  Derivative works need
      * not be licensed under similar terms.
      *
      */
     
     #include <assert.h>
     #include <stdio.h>
     #include <stdlib.h>
     #include <string.h>
     
     #include "punycode.h"
     
     /* For testing, we'll just set some compile-time limits rather than */
     /* use malloc(), and set a compile-time option rather than using a  */
     /* command-line option.                                             */
     
     enum
     {
       unicode_max_length = 256,
       ace_max_length = 256
     };
     
     static void
     usage (char **argv)
     {
       fprintf (stderr,
     	   "\n"
     	   "%s -e reads code points and writes a Punycode string.\n"
     	   "%s -d reads a Punycode string and writes code points.\n"
     	   "\n"
     	   "Input and output are plain text in the native character set.\n"
     	   "Code points are in the form u+hex separated by whitespace.\n"
     	   "Although the specification allows Punycode strings to contain\n"
     	   "any characters from the ASCII repertoire, this test code\n"
     	   "supports only the printable characters, and needs the Punycode\n"
     	   "string to be followed by a newline.\n"
     	   "The case of the u in u+hex is the force-to-uppercase flag.\n",
     	   argv[0], argv[0]);
       exit (EXIT_FAILURE);
     }
     
     
     static void
     fail (const char *msg)
     {
       fputs (msg, stderr);
       exit (EXIT_FAILURE);
     }
     
     static const char too_big[] =
       "input or output is too large, recompile with larger limits\n";
     static const char invalid_input[] = "invalid input\n";
     static const char overflow[] = "arithmetic overflow\n";
     static const char io_error[] = "I/O error\n";
     
     
     /* The following string is used to convert printable */
     /* characters between ASCII and the native charset:  */
     
     static const char print_ascii[] =
       "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"
       "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"
       " !\"#$%&'()*+,-./"
       "0123456789:;<=>?"
       "\x40ABCDEFGHIJKLMNO"
       "PQRSTUVWXYZ[\\]^_" "`abcdefghijklmno" "pqrstuvwxyz{|}~\n";
     
     
     int
     main (int argc, char **argv)
     {
       int status;
       int r;
       unsigned int input_length, output_length, j;
       unsigned char case_flags[unicode_max_length];
     
       if (argc != 2)
         usage (argv);
       if (argv[1][0] != '-')
         usage (argv);
       if (argv[1][2] != 0)
         usage (argv);
     
       if (argv[1][1] == 'e')
         {
           unsigned long input[unicode_max_length];
           unsigned long codept;
           char output[ace_max_length + 1], uplus[3];
           int c;
     
           /* Read the input code points: */
     
           input_length = 0;
     
           for (;;)
     	{
     	  r = scanf ("%2s%lx", uplus, &codept);
     	  if (ferror (stdin))
     	    fail (io_error);
     	  if (r == EOF || r == 0)
     	    break;
     
     	  if (r != 2 || uplus[1] != '+' || codept > (unsigned long) -1)
     	    {
     	      fail (invalid_input);
     	    }
     
     	  if (input_length == unicode_max_length)
     	    fail (too_big);
     
     	  if (uplus[0] == 'u')
     	    case_flags[input_length] = 0;
     	  else if (uplus[0] == 'U')
     	    case_flags[input_length] = 1;
     	  else
     	    fail (invalid_input);
     
     	  input[input_length++] = codept;
     	}
     
           /* Encode: */
     
           output_length = ace_max_length;
           status = punycode_encode (input_length, input, case_flags,
     				&output_length, output);
           if (status == PUNYCODE_BAD_INPUT)
     	fail (invalid_input);
           if (status == PUNYCODE_BIG_OUTPUT)
     	fail (too_big);
           if (status == PUNYCODE_OVERFLOW)
     	fail (overflow);
           assert (status == PUNYCODE_SUCCESS);
     
           /* Convert to native charset and output: */
     
           for (j = 0; j < output_length; ++j)
     	{
     	  c = output[j];
     	  assert (c >= 0 && c <= 127);
     	  if (print_ascii[c] == 0)
     	    fail (invalid_input);
     	  output[j] = print_ascii[c];
     	}
     
           output[j] = 0;
           r = puts (output);
           if (r == EOF)
     	fail (io_error);
           return EXIT_SUCCESS;
         }
     
       if (argv[1][1] == 'd')
         {
           char input[ace_max_length + 2], *p, *pp;
           unsigned long output[unicode_max_length];
     
           /* Read the Punycode input string and convert to ASCII: */
     
           fgets (input, ace_max_length + 2, stdin);
           if (ferror (stdin))
     	fail (io_error);
           if (feof (stdin))
     	fail (invalid_input);
           input_length = strlen (input) - 1;
           if (input[input_length] != '\n')
     	fail (too_big);
           input[input_length] = 0;
     
           for (p = input; *p != 0; ++p)
     	{
     	  pp = strchr (print_ascii, *p);
     	  if (pp == 0)
     	    fail (invalid_input);
     	  *p = pp - print_ascii;
     	}
     
           /* Decode: */
     
           output_length = unicode_max_length;
           status = punycode_decode (input_length, input, &output_length,
     				output, case_flags);
           if (status == PUNYCODE_BAD_INPUT)
     	fail (invalid_input);
           if (status == PUNYCODE_BIG_OUTPUT)
     	fail (too_big);
           if (status == PUNYCODE_OVERFLOW)
     	fail (overflow);
           assert (status == PUNYCODE_SUCCESS);
     
           /* Output the result: */
     
           for (j = 0; j < output_length; ++j)
     	{
     	  r = printf ("%s+%04lX\n",
     		      case_flags[j] ? "U" : "u", (unsigned long) output[j]);
     	  if (r < 0)
     	    fail (io_error);
     	}
     
           return EXIT_SUCCESS;
         }
     
       usage (argv);
       return EXIT_SUCCESS;		/* not reached, but quiets compiler warning */
     
     }

Example 3
=========

   This example demonstrates how the library is used to convert
internationalized domain names into ASCII compatible names.

     /* example3.c	Example code showing how to use Libidn.
      * Copyright (C) 2002  Simon Josefsson
      *
      * This file is part of GNU Libidn.
      *
      * GNU Libidn is free software; you can redistribute it and/or
      * modify it under the terms of the GNU Lesser General Public
      * License as published by the Free Software Foundation; either
      * version 2.1 of the License, or (at your option) any later version.
      *
      * GNU Libidn is distributed in the hope that it will be useful,
      * but WITHOUT ANY WARRANTY; without even the implied warranty of
      * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      * Lesser General Public License for more details.
      *
      * You should have received a copy of the GNU Lesser General Public
      * License along with GNU Libidn; if not, write to the Free Software
      * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      *
      */
     
     #include <stdio.h>
     #include <stdlib.h>
     #include <string.h>
     #include <stringprep.h> /* stringprep_locale_charset() */
     #include <idna.h> /* idna_locale_to_ace() */
     
     /*
      * Compiling using libtool and pkg-config is recommended:
      *
      * $ libtool cc -o example3 example3.c `pkg-config --cflags --libs libidn`
      * $ ./example3
      * Input domain encoded as `ISO-8859-1': www.rksmrgs.example
      * Read string (length 23): 77 77 77 2e 72 e4 6b 73 6d f6 72 67 e5 73 aa 2e 65 78 61 6d 70 6c 65
      * ACE label (length 33): 'www.iesg--rksmrgsa-0zap8p.example'
      * 77 77 77 2e 69 65 73 67 2d 2d 72 6b 73 6d 72 67 73 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
      * $
      *
      */
     
     int
     main (int argc, char *argv[])
     {
       char buf[BUFSIZ];
       char *p;
       int rc, i;
     
       printf ("Input domain encoded as `%s': ", stringprep_locale_charset ());
       fflush (stdout);
       fgets (buf, BUFSIZ, stdin);
       buf[strlen(buf)-1] = '\0';
     
       printf ("Read string (length %d): ", strlen (buf));
       for (i = 0; i < strlen (buf); i++)
         printf ("%02x ", buf[i] & 0xFF);
       printf ("\n");
     
       rc = idna_locale_to_ace (buf, &p);
       if (rc != IDNA_SUCCESS)
         {
           printf("ToASCII() failed... %d\n", rc);
           exit(1);
         }
     
       printf ("ACE label (length %d): '%s'\n", strlen (p), p);
       for (i = 0; i < strlen (p); i++)
         printf ("%02x ", p[i] & 0xFF);
       printf ("\n");
     
       free(p);
     
       return 0;
     }

Example 4
=========

   This example demonstrates how the library is used to convert ASCII
compatible names to internationalized domain names.

     /* example4.c	Example code showing how to use Libidn.
      * Copyright (C) 2002  Simon Josefsson
      *
      * This file is part of GNU Libidn.
      *
      * GNU Libidn is free software; you can redistribute it and/or
      * modify it under the terms of the GNU Lesser General Public
      * License as published by the Free Software Foundation; either
      * version 2.1 of the License, or (at your option) any later version.
      *
      * GNU Libidn is distributed in the hope that it will be useful,
      * but WITHOUT ANY WARRANTY; without even the implied warranty of
      * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      * Lesser General Public License for more details.
      *
      * You should have received a copy of the GNU Lesser General Public
      * License along with GNU Libidn; if not, write to the Free Software
      * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      *
      */
     
     #include <stdio.h>
     #include <stdlib.h>
     #include <string.h>
     #include <stringprep.h> /* stringprep_locale_charset() */
     #include <idna.h> /* idna_localeace_to_locale() */
     
     /*
      * Compiling using libtool and pkg-config is recommended:
      *
      * $ libtool cc -o example4 example4.c `pkg-config --cflags --libs libidn`
      * $ ./example4
      * Input domain encoded as `ISO-8859-1': www.iesg--rksmrgsa-0zap8p.example
      * Read string (length 33): 77 77 77 2e 69 65 73 67 2d 2d 72 6b 73 6d 72 67 73 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
      * ACE label (length 23): 'www.rksmrgsa.example'
      * 77 77 77 2e 72 e4 6b 73 6d f6 72 67 e5 73 61 2e 65 78 61 6d 70 6c 65
      * $
      *
      */
     
     int
     main (int argc, char *argv[])
     {
       char buf[BUFSIZ];
       char *p;
       int rc, i;
     
       printf ("Input domain encoded as `%s': ", stringprep_locale_charset ());
       fflush (stdout);
       fgets (buf, BUFSIZ, stdin);
       buf[strlen(buf)-1] = '\0';
     
       printf ("Read string (length %d): ", strlen (buf));
       for (i = 0; i < strlen (buf); i++)
         printf ("%02x ", buf[i] & 0xFF);
       printf ("\n");
     
       rc = idna_localeace_to_locale (buf, &p);
       if (rc != IDNA_SUCCESS)
         {
           printf("ToUnicode() failed... %d\n", rc);
           exit(1);
         }
     
       printf ("ACE label (length %d): '%s'\n", strlen (p), p);
       for (i = 0; i < strlen (p); i++)
         printf ("%02x ", p[i] & 0xFF);
       printf ("\n");
     
       free(p);
     
       return 0;
     }

Copying This Manual
*******************

GNU Free Documentation License
==============================

                        Version 1.1, March 2000
     Copyright (C) 2000 Free Software Foundation, Inc.
     59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
     
     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

  0. PREAMBLE

     The purpose of this License is to make a manual, textbook, or other
     written document "free" in the sense of freedom: to assure everyone
     the effective freedom to copy and redistribute it, with or without
     modifying it, either commercially or noncommercially.  Secondarily,
     this License preserves for the author and publisher a way to get
     credit for their work, while not being considered responsible for
     modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
     that the software does.  But this License is not limited to
     software manuals; it can be used for any textual work, regardless
     of subject matter or whether it is published as a printed book.
     We recommend this License principally for works whose purpose is
     instruction or reference.

  1. APPLICABILITY AND DEFINITIONS

     This License applies to any manual or other work that contains a
     notice placed by the copyright holder saying it can be distributed
     under the terms of this License.  The "Document", below, refers to
     any such manual or work.  Any member of the public is a licensee,
     and is addressed as "you".

     A "Modified Version" of the Document means any work containing the
     Document or a portion of it, either copied verbatim, or with
     modifications and/or translated into another language.

     A "Secondary Section" is a named appendix or a front-matter
     section of the Document that deals exclusively with the
     relationship of the publishers or authors of the Document to the
     Document's overall subject (or to related matters) and contains
     nothing that could fall directly within that overall subject.
     (For example, if the Document is in part a textbook of
     mathematics, a Secondary Section may not explain any mathematics.)
     The relationship could be a matter of historical connection with
     the subject or with related matters, or of legal, commercial,
     philosophical, ethical or political position regarding them.

     The "Invariant Sections" are certain Secondary Sections whose
     titles are designated, as being those of Invariant Sections, in
     the notice that says that the Document is released under this
     License.

     The "Cover Texts" are certain short passages of text that are
     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
     that says that the Document is released under this License.

     A "Transparent" copy of the Document means a machine-readable copy,
     represented in a format whose specification is available to the
     general public, whose contents can be viewed and edited directly
     and straightforwardly with generic text editors or (for images
     composed of pixels) generic paint programs or (for drawings) some
     widely available drawing editor, and that is suitable for input to
     text formatters or for automatic translation to a variety of
     formats suitable for input to text formatters.  A copy made in an
     otherwise Transparent file format whose markup has been designed
     to thwart or discourage subsequent modification by readers is not
     Transparent.  A copy that is not "Transparent" is called "Opaque".

     Examples of suitable formats for Transparent copies include plain
     ASCII without markup, Texinfo input format, LaTeX input format,
     SGML or XML using a publicly available DTD, and
     standard-conforming simple HTML designed for human modification.
     Opaque formats include PostScript, PDF, proprietary formats that
     can be read and edited only by proprietary word processors, SGML
     or XML for which the DTD and/or processing tools are not generally
     available, and the machine-generated HTML produced by some word
     processors for output purposes only.

     The "Title Page" means, for a printed book, the title page itself,
     plus such following pages as are needed to hold, legibly, the
     material this License requires to appear in the title page.  For
     works in formats which do not have any title page as such, "Title
     Page" means the text near the most prominent appearance of the
     work's title, preceding the beginning of the body of the text.

  2. VERBATIM COPYING

     You may copy and distribute the Document in any medium, either
     commercially or noncommercially, provided that this License, the
     copyright notices, and the license notice saying this License
     applies to the Document are reproduced in all copies, and that you
     add no other conditions whatsoever to those of this License.  You
     may not use technical measures to obstruct or control the reading
     or further copying of the copies you make or distribute.  However,
     you may accept compensation in exchange for copies.  If you
     distribute a large enough number of copies you must also follow
     the conditions in section 3.

     You may also lend copies, under the same conditions stated above,
     and you may publicly display copies.

  3. COPYING IN QUANTITY

     If you publish printed copies of the Document numbering more than
     100, and the Document's license notice requires Cover Texts, you
     must enclose the copies in covers that carry, clearly and legibly,
     all these Cover Texts: Front-Cover Texts on the front cover, and
     Back-Cover Texts on the back cover.  Both covers must also clearly
     and legibly identify you as the publisher of these copies.  The
     front cover must present the full title with all words of the
     title equally prominent and visible.  You may add other material
     on the covers in addition.  Copying with changes limited to the
     covers, as long as they preserve the title of the Document and
     satisfy these conditions, can be treated as verbatim copying in
     other respects.

     If the required texts for either cover are too voluminous to fit
     legibly, you should put the first ones listed (as many as fit
     reasonably) on the actual cover, and continue the rest onto
     adjacent pages.

     If you publish or distribute Opaque copies of the Document
     numbering more than 100, you must either include a
     machine-readable Transparent copy along with each Opaque copy, or
     state in or with each Opaque copy a publicly-accessible
     computer-network location containing a complete Transparent copy
     of the Document, free of added material, which the general
     network-using public has access to download anonymously at no
     charge using public-standard network protocols.  If you use the
     latter option, you must take reasonably prudent steps, when you
     begin distribution of Opaque copies in quantity, to ensure that
     this Transparent copy will remain thus accessible at the stated
     location until at least one year after the last time you
     distribute an Opaque copy (directly or through your agents or
     retailers) of that edition to the public.

     It is requested, but not required, that you contact the authors of
     the Document well before redistributing any large number of
     copies, to give them a chance to provide you with an updated
     version of the Document.

  4. MODIFICATIONS

     You may copy and distribute a Modified Version of the Document
     under the conditions of sections 2 and 3 above, provided that you
     release the Modified Version under precisely this License, with
     the Modified Version filling the role of the Document, thus
     licensing distribution and modification of the Modified Version to
     whoever possesses a copy of it.  In addition, you must do these
     things in the Modified Version:

       A. Use in the Title Page (and on the covers, if any) a title
          distinct from that of the Document, and from those of
          previous versions (which should, if there were any, be listed
          in the History section of the Document).  You may use the
          same title as a previous version if the original publisher of
          that version gives permission.

       B. List on the Title Page, as authors, one or more persons or
          entities responsible for authorship of the modifications in
          the Modified Version, together with at least five of the
          principal authors of the Document (all of its principal
          authors, if it has less than five).

       C. State on the Title page the name of the publisher of the
          Modified Version, as the publisher.

       D. Preserve all the copyright notices of the Document.

       E. Add an appropriate copyright notice for your modifications
          adjacent to the other copyright notices.

       F. Include, immediately after the copyright notices, a license
          notice giving the public permission to use the Modified
          Version under the terms of this License, in the form shown in
          the Addendum below.

       G. Preserve in that license notice the full lists of Invariant
          Sections and required Cover Texts given in the Document's
          license notice.

       H. Include an unaltered copy of this License.

       I. Preserve the section entitled "History", and its title, and
          add to it an item stating at least the title, year, new
          authors, and publisher of the Modified Version as given on
          the Title Page.  If there is no section entitled "History" in
          the Document, create one stating the title, year, authors,
          and publisher of the Document as given on its Title Page,
          then add an item describing the Modified Version as stated in
          the previous sentence.

       J. Preserve the network location, if any, given in the Document
          for public access to a Transparent copy of the Document, and
          likewise the network locations given in the Document for
          previous versions it was based on.  These may be placed in
          the "History" section.  You may omit a network location for a
          work that was published at least four years before the
          Document itself, or if the original publisher of the version
          it refers to gives permission.

       K. In any section entitled "Acknowledgments" or "Dedications",
          preserve the section's title, and preserve in the section all
          the substance and tone of each of the contributor
          acknowledgments and/or dedications given therein.

       L. Preserve all the Invariant Sections of the Document,
          unaltered in their text and in their titles.  Section numbers
          or the equivalent are not considered part of the section
          titles.

       M. Delete any section entitled "Endorsements".  Such a section
          may not be included in the Modified Version.

       N. Do not retitle any existing section as "Endorsements" or to
          conflict in title with any Invariant Section.

     If the Modified Version includes new front-matter sections or
     appendices that qualify as Secondary Sections and contain no
     material copied from the Document, you may at your option
     designate some or all of these sections as invariant.  To do this,
     add their titles to the list of Invariant Sections in the Modified
     Version's license notice.  These titles must be distinct from any
     other section titles.

     You may add a section entitled "Endorsements", provided it contains
     nothing but endorsements of your Modified Version by various
     parties--for example, statements of peer review or that the text
     has been approved by an organization as the authoritative
     definition of a standard.

     You may add a passage of up to five words as a Front-Cover Text,
     and a passage of up to 25 words as a Back-Cover Text, to the end
     of the list of Cover Texts in the Modified Version.  Only one
     passage of Front-Cover Text and one of Back-Cover Text may be
     added by (or through arrangements made by) any one entity.  If the
     Document already includes a cover text for the same cover,
     previously added by you or by arrangement made by the same entity
     you are acting on behalf of, you may not add another; but you may
     replace the old one, on explicit permission from the previous
     publisher that added the old one.

     The author(s) and publisher(s) of the Document do not by this
     License give permission to use their names for publicity for or to
     assert or imply endorsement of any Modified Version.

  5. COMBINING DOCUMENTS

     You may combine the Document with other documents released under
     this License, under the terms defined in section 4 above for
     modified versions, provided that you include in the combination
     all of the Invariant Sections of all of the original documents,
     unmodified, and list them all as Invariant Sections of your
     combined work in its license notice.

     The combined work need only contain one copy of this License, and
     multiple identical Invariant Sections may be replaced with a single
     copy.  If there are multiple Invariant Sections with the same name
     but different contents, make the title of each such section unique
     by adding at the end of it, in parentheses, the name of the
     original author or publisher of that section if known, or else a
     unique number.  Make the same adjustment to the section titles in
     the list of Invariant Sections in the license notice of the
     combined work.

     In the combination, you must combine any sections entitled
     "History" in the various original documents, forming one section
     entitled "History"; likewise combine any sections entitled
     "Acknowledgments", and any sections entitled "Dedications".  You
     must delete all sections entitled "Endorsements."

  6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other
     documents released under this License, and replace the individual
     copies of this License in the various documents with a single copy
     that is included in the collection, provided that you follow the
     rules of this License for verbatim copying of each of the
     documents in all other respects.

     You may extract a single document from such a collection, and
     distribute it individually under this License, provided you insert
     a copy of this License into the extracted document, and follow
     this License in all other respects regarding verbatim copying of
     that document.

  7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other
     separate and independent documents or works, in or on a volume of
     a storage or distribution medium, does not as a whole count as a
     Modified Version of the Document, provided no compilation
     copyright is claimed for the compilation.  Such a compilation is
     called an "aggregate", and this License does not apply to the
     other self-contained works thus compiled with the Document, on
     account of their being thus compiled, if they are not themselves
     derivative works of the Document.

     If the Cover Text requirement of section 3 is applicable to these
     copies of the Document, then if the Document is less than one
     quarter of the entire aggregate, the Document's Cover Texts may be
     placed on covers that surround only the Document within the
     aggregate.  Otherwise they must appear on covers around the whole
     aggregate.

  8. TRANSLATION

     Translation is considered a kind of modification, so you may
     distribute translations of the Document under the terms of section
     4.  Replacing Invariant Sections with translations requires special
     permission from their copyright holders, but you may include
     translations of some or all Invariant Sections in addition to the
     original versions of these Invariant Sections.  You may include a
     translation of this License provided that you also include the
     original English version of this License.  In case of a
     disagreement between the translation and the original English
     version of this License, the original English version will prevail.

  9. TERMINATION

     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided for under this License.  Any other
     attempt to copy, modify, sublicense or distribute the Document is
     void, and will automatically terminate your rights under this
     License.  However, parties who have received copies, or rights,
     from you under this License will not have their licenses
     terminated so long as such parties remain in full compliance.

 10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See
     `http://www.gnu.org/copyleft/'.

     Each version of the License is given a distinguishing version
     number.  If the Document specifies that a particular numbered
     version of this License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that specified version or of any later version that has been
     published (not as a draft) by the Free Software Foundation.  If
     the Document does not specify a version number of this License,
     you may choose any version ever published (not as a draft) by the
     Free Software Foundation.

ADDENDUM: How to use this License for your documents
----------------------------------------------------

   To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

       Copyright (C)  YEAR  YOUR NAME.
       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.1
       or any later version published by the Free Software Foundation;
       with the Invariant Sections being LIST THEIR TITLES, with the
       Front-Cover Texts being LIST, and with the Back-Cover Texts
       being LIST.  A copy of the license is included in the section
       entitled ``GNU Free Documentation License''.

   If you have no Invariant Sections, write "with no Invariant Sections"
instead of saying which ones are invariant.  If you have no Front-Cover
Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
LIST"; likewise for Back-Cover Texts.

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.

Index
*****

AIX:
          See ``Supported Platforms''.
Compiling your application:
          See ``Building the source''.
Debian:
          See ``Supported Platforms''.
Examples:
          See ``Examples''.
FDL, GNU Free Documentation License:
          See ``GNU Free Documentation License''.
FreeBSD:
          See ``Supported Platforms''.
HP-UX:
          See ``Supported Platforms''.
IDNA Functions:
          See ``IDNA Functions''.
IRIX:
          See ``Supported Platforms''.
NetBSD:
          See ``Supported Platforms''.
OpenBSD:
          See ``Supported Platforms''.
Punycode Functions:
          See ``Punycode Functions''.
RedHat:
          See ``Supported Platforms''.
Reporting Bugs:
          See ``Bug Reports''.
Solaris:
          See ``Supported Platforms''.
Stringprep Functions:
          See ``Stringprep Functions''.
SuSE:
          See ``Supported Platforms''.
SuSE Linux:
          See ``Supported Platforms''.
Tru64:
          See ``Supported Platforms''.
Windows:
          See ``Supported Platforms''.
