********************************************************************** FTSC FIDONET TECHNICAL STANDARDS COMMITTEE ********************************************************************** Publication: FRL-1020 Revision: 1 Title: Character set definition in Fidonet messages Author: Peter Karlsson Date: 9 April 2012 ---------------------------------------------------------------------- Contents: 1. Introduction 2. Format of the identifier 3. Supported levels 4. Supported character sets 5. Obsolete identifiers 6. Notes ---------------------------------------------------------------------- Status of this document ----------------------- Status of this document ----------------------- This document is a Fidonet Reference Library Document (FRL). This document preserves FSP-1013 which was with some small modifi- cations and additions promoted to a Fidonet standard and documented as FTS-5003. This document is released to the public domain, and may be used, copied or modified for any purpose whatever. 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: Where 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 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: pk@abc.se * These contact data are out of date. See FTS-5003 for recent data. B. Acknowledgements ------------------- Duncan McNutt (original FSC-0054 author). C. History ---------- Of FSP-1013: Rev.1, 19990904: Based on FSC-0054, by Peter Karlsson Of FRL-1020 20120409 preserving FSP-1013.