Libidn doc/tld/README -- Notes and definition of the TLD tables.
Copyright (C) 2004-2025 Simon Josefsson
Copyright (C) 2004  Free Software Foundation, Inc
See the end for copying conditions.

This directory contain tables that specify which characters are valid
for each TLD.  Each table is stored in a file XX.tld where XX doesn't
really matter, but is recommended to be the TLD name.  For example,
the TLD table for .FR is stored in the file "fr.tld".

The library finds all files matching *.tld automatically, so if you
install a file you only need to remove lib/tlds.c and type 'make' and
it will be incorporated in the library.

Experimental tables for various TLDs can be found at
<https://github.com/gnuthor/tldchk>.

The format for the files are as follows.  Empty lines or those
starting with '#' are ignored.  It is highly recommended to discuss
matters in a comment; to give the URL to the source of the table,
mention the copyright and copying conditions of the tables, etc.
Normal lines consist of valid Unicode code points for the TLD,
expressed as single numbers (like 123, 0xff, 0100) or inclusive
intervals (112-344 0xff-0100) using the usual C decimal, octal or hex
notations.

Each TLD file must contain one line on the format 'tld XX'.  The XX
should be the TLD name that the file defines.  This is the string that
is used in the generated C source code.

If definitions are shared among several TLDs or are constructed from
standard Unicode blocks, put the building blocks in a file of its own
and include it using 'include FILENAME' on a line by itself.

All files, even included files, MUST contain a line 'version FOO'
where FOO is a human readable string that should be possible to use in
a string comparison to detect when the table has changed.  The version
number must be changed whenever a backwards incompatible change is
made to the file.  Don't change the version number just because the
comments are changed, or there is a new release of the library.

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