**********************************************************************
FTSC                             FIDONET TECHNICAL STANDARDS COMMITTEE
**********************************************************************

Publication:    FSP-1013
Revision:       1
Title:          Character set definition in Fidonet messages
Author:         Peter Karlsson
Revision Date:  04 September 1999
Expiry Date:    04 September 2199
----------------------------------------------------------------------
Contents:
               1. Introduction
               2. Format of the identifier
               3. Supported levels
               4. Supported character sets
               5. Obsolete identifiers
               6. Notes
----------------------------------------------------------------------


Status of this document
-----------------------

 This document suggests a proposed protocol for the FidoNet(r)
 community, and requests discussion and suggestions for improvements.
 Distribution of this document is unlimited.


Abstract
--------

 This document defines the identifiers that are used to indicate the
 character set used within messages that are distributed in Fidonet.

 There has been many attempts on defining a common standard on what
 character set is used in Fidonet distributed messages. The only one
 that has gained widespread is the "CHRS" standard, described in
 FSC-0054. This document tries to describe the current usage, as
 well as standardizing the parts of it that was ambigously defined.


1. Introduction
---------------

 As Fidonet is an international network, one has to consider that
 not all people speak English. Many languages also have alphabets
 that are either bigger than the standard English alphabet, or
 completely different. To keep track of which character set is used
 for a particular message, this documents describes a way to identify
 this to the reader.


2. Format of identifier
-----------------------

 The CHRS control line is formatted as follows:

       ^ACHRS: <identifier> <level>

 Where <identifier> is a character string of no more than eight (8)
 characters identifying the character set to use, and level is a
 numeric value describing what level of CHRS this message is written
 in.

 For backward compatibility, the use of "CHARSET" instead of "CHRS"
 should be supported when reading messages.

 Some current implementations do not add the required <level> field.
 Implemetations of this document should allow for this usage, but
 never write such control lines themselves.

 Incoming messages without "CHRS" control lines should be considered
 as being written in the area's default character set (normally
 ASCII, IBM codepage 437, LATIN-1 or similar).


3. Supported levels
-------------------

 These levels are the one that are implemented in current software:

Level 0
-------

 This level is for messages containing of pure seven-bit ASCII only.
 Outgoing messages in pure ASCII need not be identified by a "CHRS"
 control line, but if they are, they should be indicated as
 "ASCII 1" (not "ASCII 0").

Level 1
-------

 First level of internationalization, using seven bit character sets.
 Most of these are based on US ASCII, with minor internationalization
 variations.

Level 2
-------

 Second level of internationalization, using eight bit character
 sets.

 This level adds support for character sets that use "extended
 ASCII", i.e codes with the most significant bit set. The character
 sets in level two are all based on ASCII (the codes 0-127 coincides
 with ASCII).

Level 3 and above
-----------------

 Level 3 or higher as specified by FSC-54 has no known current
 implementation, because of which this document are considered
 reserved for future use.

 Level 3 would be suited for a Unicode (ISO 10646) implementation.
 Because of limitations of currently available Fidonet packet
 standards, it is not at the time of writing viable to specify how
 this should work.


4. Supported character sets
---------------------------

 These character sets are defined at the moment:

 Identifier  Character set
 ----------  -------------

   Level 1 character sets (seven-bit)

 ASCII       ISO 646-1 (US ASCII)
 DUTCH       ISO 646 Dutch
 FINNISH     ISO 646-10 (Swedish/Finnish)
 FRENCH      ISO 646 French
 CANADIAN    ISO 646 Canadian
 GERMAN      ISO 646 German
 ITALIAN     ISO 646 Italian
 NORWEIG     ISO 646 Norweigian
 PORTU       ISO 646 Protuguese
 SPANISH     ISO 646 Spanish
 SWEDISH     ISO 646-10 (Swedish/Finnish)
 SWISS       ISO 646 Swiss
 UK          ISO 646 UK

   Level 1 known depreciated character set identifiers

 ISO-10      ISO 646-10 (Swedish/Finnish)

   Level 2 character sets (eight-bit, ASCII based)

 CP437       IBM codepage 437 (Western European)
 CP850       IBM codepage 850 (Latin-1)
 CP865       IBM codepage 865 (Nordic)
 CP866       IBM codepage 866 (Russian)

 LATIN-1     ISO 8859-1 (Western European)
 LATIN-2     ISO 8859-2 (Eastern European)
 LATIN-5     ISO 8859-9 (Turkish)

 MAC         MacIntosh character set

   Level 2 obsolete character set identifiers (see note)

 IBMPC       IBM PC character set
 +7_FIDO     IBM codepage 866


5. Obsolete indentifiers
------------------------

 Since the "IBMPC" identifier, initially used to indicate IBM
 codepage 437, eventually evolved into identifying "any IBM
 codepage", there exists in some implementations an additional
 control line, "CODEPAGE", identifying the messages codepage:

       ^ACODEPAGE: xxx

 This use is depreciated in favour of the "CPxxx" identifiers
 defined above. If found in incoming messages, however, it should be
 used as an override of the "CHRS: IBMPC" identifier.

 The character set "+7_FIDO" is currently in use as an identifier for
 CP866. This use is depreciated, and "CP866" is recommended instead.
 Implementations should treat "+7_FIDO" as a synonym for "CP866".

 FSC-54 also defined control lines for style changes, "CHRC". These
 are not implemented in any software known to the author, and are
 depreciated.

 Levels 3 and 4, as defined by FSC-54, are also considered "obsolete"
 since there currently are no known implementations of them. All
 levels not documented here are considered reserved for future use.


6. Notes
--------

 The character set identifier applies to all parts of the message,
 including the header information, and the tear and Origin lines.

 FSC-54 documents file formats for mapping files that could be used
 for storing character translation data. These are not documented
 here.


A. Author contact data
----------------------

 Peter Karlsson
 Fidonet: 2:206/221
 E-mail: [email protected]


B. Acknowledgements
-------------------

 Duncan McNutt (original FSC-0054 author).


C. History
----------

 Rev.1, 19990904: Based on FSC-0054, by Peter Karlsson

You are viewing proxied material from gopher.altexxanet.org. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.