
About .kmap files

   Mind Tuning: The Unicode theory and Unicode-savvy text editors make
   a clear (and useful) distinction among

	1.  the keyboard key(s) typed
	2.  the Unicode character(s) entered and stored in a file or
	    buffer, and 
	3.  the glyph(s) (i.e. the graphic shapes) that are displayed. 

   Rendering: The mapping between the Unicode characters stored in a
   file or buffer and the display of glyphs is handled by a Rendering
   Engine, which can vary considerably in complexity, being fairly
   straightforward for Latin scripts and very complex for Arabic or
   Devanagari.  Most users should be able to assume that the Rendering
   Engine is taken care of.

   Input Method: The mapping between the keyboard key(s) typed and the
   Unicode character(s) entered in a file or buffer is defined by an
   Input Method.

   Defining Input Methods: In Yudit, .kmap ("keymap") files with names
   like Arabic.kmap, Dutch.kmap and Hungarian.kmap provide the mapping
   between the key or keys physically typed by the user and the
   desired Unicode character(s) to be inserted in the edit buffer.
   Each .kmap file defines an Input Method, and almost 100 .kmap files
   are supplied with the Yudit download.

   Yudit users can switch among the input methods at will to
   facilitate entering text in multiple languages/scripts, even within
   the same document.  Users can also define their own .kmap files to
   handle new exotic scripts or simply to define new entry methods
   that satisfy their own needs and tastes.  For a single script,
   e.g. Arabic, Chinese, Esperanto or Hangul, there may be different
   kmap-defined input methods that appeal to different users.  For
   example, Yudit comes supplied with three different .kmap files for
   Arabic input:

	Arabic.kmap
	ArabicTranslit.kmap
	ArabicKeyboard.kmap

   and you might not like any of them.  That's OK, because it is
   fairly simple to write your own .kmap file.

Writing a New .kmap File

   To write a new .kmap file, the user should first study the Unicode
   character implementation of the target script to determine the full
   set of Unicode values that need to be entered.  For a Roman-based
   script like Esperanto, most of the characters are standard lower
   ASCII Roman and need no special handling; you type 'b' in Yudit and
   a 'b' gets inserted into the buffer.  But Esperanto orthography has
   six oddly accented letters that need to be entered via a
   .kmap-defined input method.  The six letters can be uppercase or
   lowercase, resulting in 12 separate characters, and these
   characters are defined in Unicode.  For example, Esperanto
   orthography includes a 'c' letter with a circumflex accent.  The
   Unicode codepoint for the lowercase version is 0x0109, and the
   codepoint for the uppercase version is 0x0108.  In the Unicode
   specification, these are listed as

   Codepoint       Official Unicode Name

   0x0108          LATIN CAPITAL LETTER C WITH CIRCUMFLEX
   0x0109          LATIN SMALL LETTER C WITH CIRCUMFLEX

   As there is no key on the ASCII keyboard for entering either of
   these characters directly, the most obvious solution is to enter
   them using multiple keystrokes.  The basic syntax of each entry in
   the .kmap file is

   " InputKeystroke(s) = OutputUnicodeCharacter(s)" ,

   surrounded by double quotes and terminated with a comma.  Spaces
   around the equal sign and between the symbols are optional and are
   ignored if present.  (Such spaces can improve the human readability
   of the file.)  The format of these entries will be discussed in
   detail below.

   The Esperanto.kmap file supplied with Yudit includes the following
   straightforward entries.  [The terminating commas do not appear to
   be absolutely necessary to the current parser, but technically they
   should be present.]

   "cx = 0x0109" , // LATIN SMALL LETTER C WITH CIRCUMFLEX
   "Cx = 0x0108" , // LATIN CAPITAL LETTER C WITH CIRCUMFLEX
   "CX = 0x0108" , // LATIN CAPITAL LETTER C WITH CIRCUMFLEX

   The InputKeystrokes are 8-bit values, entered either as printable
   letters like c and x (as in this example) or by their numerical
   ASCII values (see formats and special cases below).  The output
   characters are 16-bit Unicode values, notated 0xHHHH, where H is a
   hex digit 0 to F.  These entries have optional comments starting
   with // and continuing to the end of line.

   When the Esperanto entry method compiled from this source file is
   selected and the user types c followed by x, the sequence of these
   two keystrokes will be detected and intercepted by the input
   method, and a single Unicode character 0x0109 will be inserted into
   the edit buffer.  (And if a suitable font is installed, Yudit will
   render the appropriate glyph on the screen.)  Similarly, if the
   user types big C followed by either little x or big X, then the
   sequence will be intercepted and mapped into a single 0x0108
   Unicode character.  Thus multiple input keystrokes can be mapped to
   a single Unicode character, and there can be multiple sequences
   that map to the same Unicode character.

   Input keystroke sequences should be chosen with care to avoid
   ambiguity and clashes; for human convenience, the input sequences
   should also be maximally mnemonic.
   
   The choice of "cx" is a very suitable sequence for Esperanto entry
   of c-with-circumflex because

   1.  The letter x is not normally used in Esperanto orthography, and
   2.  There is already a well-known convention for typing Esperanto 
       that uses "cx" for c-with-circumflex when the real letter is 
       not available.

   However, there are other conventions for typing Esperanto, and some
   other user might prefer to define a slightly different Esperanto
   kmap file to satisfy their own taste and habits.  The following
   entries, for example, could be put into a different EsperantoB.kmap
   file, or even added to the original Esperanto.kmap file.

   "c^ = 0x0109" , // LATIN SMALL LETTER C WITH CIRCUMFLEX
   "C^ = 0x0108" , // LATIN CAPITAL LETTER C WITH CIRCUMFLEX

   If such entries were defined, the typing c followed by ^ would
   result in Unicode character 0x0109 being inserted in the buffer.
   Similar for C followed by ^.

   The mappings can also be one-InputKey-to-one-UnicodeCharacter, and
   this is very common with keymaps for non-Roman scripts.  Arabic has
   a letter named siin that sounds like 's' and one named raa' that
   sounds like 'r'.  In ArabicTranslit.kmap, which as its name implies
   is based on a Roman transliteration, one finds the following
   straightforward one-to-one mappings.

   "s = 0x0633" ,  // type 's', get Unicode Arabic siin character
   "r = 0x0631" ,  // type 'r', get Unicode Arabic raa' character

   (In this case and elsewhere, one must study the Unicode
   documentation to see what the Unicode codepoint values are; in this
   case, you simply have to look up the information that Arabic siin
   has value 0x0633 and Arabic raa' has the value 0x0631. The Unicode
   charts for Arabic and other languages are easily examined starting
   from http://www.unicode.org/charts/)

   An Arabic keymap like this one, covering a whole Roman
   transliteration system, would appeal only to those people who know
   and like that particular transliteration.  Those who prefer a
   different transliteration should define their own keymap.  The only
   formal restriction for a new transliteration is that it be
   unambiguously mappable into proper Arabic Unicode characters.

   Other people entering Arabic might already be used to the keyboard
   layout on the PC or the Mac, and they might prefer to define
   keymaps that correspond to their favorite keyboard layouts (rather
   than to some kind of Roman transliteration).

   It is also conceivable that one (or multiple) input keystrokes
   could be mapped to multiple Arabic Unicode characters.  For
   example, the Arabic sequence of characters laam followed by a bare
   'alif character is properly and preferably encoded in a file or
   buffer just like that, as 0x0644 (laam) followed by 0x0627 (bare
   'alif).  One can therefore simply type laam, followed by 'alif, but
   suppose that some user preferred to think of them as a unit and
   preferred to enter them together with a single keystroke, say X.
   In such a case, the following one-to-many entry in a .kmap file
   would be appropriate:

   "X = 0x0644 0x0627" ,  // type just X to enter laam followed by 'alif

   Remember that Unicode makes a distinction between the key(s) typed,
   the Unicode character(s) encoded, and the glyph(s) rendered.
   Whether the user chooses to type laam followed by 'alif, or both at
   once using the shortcut defined just above, the Unicode characters
   inserted into the file or buffer should be the same.  Unicode
   doesn't care how you _enter_ the characters--it simply defines what
   the encoded file should look like.

   Arabic orthography requires that laam followed by 'alif be
   _rendered_ together, and all Arabic fonts supply special glyphs for
   rendering the laam-'alif sequences.  But the font-and-rendering
   considerations are altogether separate from the entry and encoding,
   and in a properly set up Arabic-capable system, the user should not
   have to worry about the rendering.

Converting .kmap Files to .my Files

   .kmap files are the human-edited and human-readable _source_ files
   for keyboard mappings.  Yudit, however, really works with .my
   files, which must be generated from the .kmap files.

   Study some of the .kmap files provided with the yudit release. By
   default, the yudit installation "prefix" is /usr, and the yudit
   executable is installed in <prefix>/bin/yudit, which by default is
   /usr/bin/yudit.  The .kmap source files are stored in
   <prefix>/share/yudit/src/ and the .my files for the whole site are
   stored in <prefix>/share/yudit/data/.  (During installation, the
   'prefix' variable may be modified manually, in which case the
   relevant bin and share directories may be somewhere other than
   /usr, which is the default prefix.)

   Files with names like Esperanto.kmap and Georgian.kmap are source
   files, written using any convenient text editor.  To be used by
   Yudit, an .my file must be generated from the .kmap source file
   according to the following example, using the 'mytool' program
   supplied with Yudit.  Let's assume that we have just written
   Georgian2.kmap to define a new input method for Georgian.

   $ mytool -type kmap -kmap Georgian2.kmap -rkmap Georgian2.kmap -write Georgian2.my

   If this new input method is intended only for private use by one
   user, then the user should copy the Georgian2.my file to the
   directory ~/.yudit/data/, i.e. to the directory named 'data', under
   the directory named ".yudit", which is in the user's own home
   directory.

   If the new entry method is intended for your whole site, then copy
   it to <prefix>/share/yudit/data/, which by default is
   /usr/share/yudit/data/.

More Detail on the Syntax of .kmap Files:

   Comments: Comments in .kmap files start with // and continue to the
   end of line.  The sequence // is therefore "special" to the parser.
   It's a good idea to comment each entry.

   Mapping Entries: There can be only one entry (mapping) to a line.
   Each entry must be surrounded by double quotes.  Technically, each
   entry should also be terminated with a comma.

   Each entry is of the form:

   " InputSymbol(s) = OutputSymbol(s) " ,

   where the Input is one or more 8-bit ASCII keystrokes, represented
   as printable ASCII characters, or as octal, decimal or hexadecimal
   numbers.  Eight-bit hexadecimal numbers are represented as 0xHH,
   where H is a hex digit from 0 to F.  Octal-format numbers start
   with \0, e.g. \037.  The Input and Output symbols are separated by
   an equal sign.  The Output consists of one or more 16-bit _Unicode_
   characters, each represented as 0xHHHH, where H is a hexadecimal
   digit 0 to F.  Spaces around the equal sign and between symbols are
   ignored.

   From the point of view of the Input Method, the Input Symbols are
   keystrokes coming from the user; the Output Symbols are the Unicode
   characters to be inserted into the Yudit edit buffer.

   The following symbols are "special" inside .kmap files and require
   special attention:

   "    double quotes (used to surround an entry)
   =    equal sign (used to separate Input Symbols and Output Symbols)
        space (ignored around the equal sign and between symbols)

   +    plus sign (interpreted by default as a positive prefix to a number)
   -    minus sign (interpreted by default as a negative prefix to a number)
   \    backslash (used to literalize a special symbol)

   Th special symbols are literalized, where necessary, by preceding
   them with the backslash "literalizer" symbol; e.g. \= denotes a
   literal equal sign.  The literal backslash itself is notated \\.

   Examples:
	" s = 0x0633 "       ,  // one to one
        " cx = 0x0109 "      ,  // many to one
        " \= = 0x0109 "      ,  // type a literal equal sign to input 0x0109
        " \\ ~ n = 0x00f1 "  ,  // allow LaTeX-like input of n-with-tilde;
                                // the user types literal \ then ~ then n
        " \\ \" a = 0x00E4 " ,  // allow LaTeX-like input of a-with-dieresis;
                                // the user types literal \ then literal "
                                //   then a to input Unicode a-with-dieresis
                                //   (a with two dots above)
	" \+u = 0x00FC "     ,  // user types literal + followed by u
		                // to input 0x00FC, which is u with dieresis 
				// (two dots above)
        " X = 0x0644 0x0627 ",  // one to many
        " 0x32 = 0x0662 "    ,  // type ASCII '2' get ARABIC-INDIC DIGIT 2

   Literal double quote: Each whole entry is surrounded by double
   quotes, so the double quote is "special" in .kmap files.  A literal
   double quote can be included inside an entry by typing \", where
   the backslash is the escape or "literalizing" character.  Another
   way to indicate a literal double quote is to give its 8-bit lower
   ASCII value, e.g.

        " \\ 0x22 a = 0x00E1 " ,  // 0x22 is the literal double quote symbol

   Literal backslash: To indicate a literal backslash as input, use \\
   or indicate the 8-bit ASCII numeric value.

        " \\ \" a = 0x00E4 "     ,  //  \\ denotes a literal backslash symbol
        " 0x5c 0x22 a = 0x00E1 " ,  //  equivalent to the entry just above

   Similarly, the equal sign separates the Input and Output; where
   necessary, a literal input equal sign is indicated as \= or \0x3D.

        " \= = 0x2345 "   ,
        " 0x3D = 0x2345 " ,  // 0x3d is the literal equal sign

   The + and - can are interpreted by default by the parser as part of
   a numerical value, so if they are intended as literal input, then
   they should be literalized in the usual ways, as in this example
   from Georgian.kmap

        "\+z = 0x10df " ,

   or using the ASCII value of the plus sign (0x2B)

        " 0x2b z = 0x10df " ,
  

   Literal white spaces: Whitespace between between characters in a
   kmap entry are normally ignored; this allows you to space out the
   input sequences for better human readability.  To notate a literal
   space as part of the Input, literalize it with a preceding
   backslash or indicate the 8-bit ASCII value.

        " \  = 0x0020 "   ,  // space literalized with preceding backslash
        " 0x20 = 0x0020 " ,  // 0x20 is the space ASCII value

   Digits: By default a string segment that starts with a digit 0-9 is
   considered a numeric value, not the literal symbols 0-9.  To
   indicate the input of a literal digit, indicate its 8-bit ASCII
   value.

        " 0x32 = 0x0662 " , // 0x32 is the ASCII value of '2'

   Number formats. Input keystrokes can be notated as octal, decimal
   or hexadecimal numbers, e.g. a period (full stop) could be notated
   equivalently as 46 (decimal), \056 (octal) or 0x2E.

   More Examples, taken from Kana.kmap:

        "\033 KE=0x30F5",   // SMALL KE
        "\"R=0x201D",       // RIGHT DOUBLE QUOTATION MARK
        "kke=0x3063 0x3051",
        "0x20 = 0x201D",    // INPUT LITERAL BLANK 
        "0x3D=0x003D",      // INPUT '=' SIGN THIS WAY


   The // sequence is special in kmap files, being the introducer of a
   comment.  If you want the sequence // as part of the Input, then
   the two slashes need to be separated by a space, e.g

        "&/ /=0x005C",      // YUDIT NEEDS SPACE BETWEEN / /
                            // to avoid treating // as the comment introducer

Yudit Strategy for Input Matching

   Clashes: It is illegal to have the same input sequence map into two
   different outputs.

        // this is an illegal clash
        " cx = 0x0109 " ,
        " cx = 0x0108 " ,

   Where multiple input sequences start with the same substring but
   have different lengths, the "greedy" matching algorithm prefers
   the longest match.  The Esperanto mapping for c-with-circumflex
   could conceivably be done as follows:

        " cx = 0x0109 "  , // lowercase c with circumflex
        " cxx = 0x0108 " , // uppercase C with circumflex

   Then if the user typed c, x, and anything but another x, the value
   0x0109 would be inserted in the buffer.  If the user typed c, x,
   and x, then the greedy algorithm would match the longer input
   sequence and insert 0x0108 into the buffer.  (Such tricks are
   possible, but are hardly recommended.)

Sub-translations:

   "Sub-translations" are currently used only for the Yudit-supplied
   Hangul-entry keymap (for Korean orthography) and for the
   Yudit-supplied Unicode-entry keymap; most users don't need to know
   about sub-translations.  [This part of the documentation should be
   reviewed and expanded.  I may have completely misunderstood it.]

   For entering whole Hangul characters, one can use a notation
   involving "sub-translations".  If the translation can be broken
   down to (maximum 5) sub-translations then the first line in the
   .kmap file may contain:

        "string1+string2+string3...",

   The subsequent lines between "begin string1", and "end string1"
   contain the sub-translation lines. The resulting Unicode number is
   the value of the sub-translations added up.

        Sub-translation may contain empty strings
        "=0x0021",
        but consecutive ones cannot. 

   Matching strategy for sub-translations: When the first
   sub-translation would match the null string, one character may be
   borrowed from the previous translation.


Autoshaping information

   [This section needs to be reviewed and expanded.]

   The Yudit-supplied Arabic.kmap and ArabicTranslit.kmap files
   contain "shaping" information, presumably for proper rendering of
   Arabic.  (Many special ligatures are possible in Arabic rendering,
   but only the laam+alif ones are absolutely required.  The following
   four mysterious entries would appear to indicate the entry
   sequences and Unicode value sequences that require special
   rendering.)

   // Shaping part using shape.mys. Autogenerated.
   //
   "l aM=0x0644 0x0622", // ?? LAM ALEF WITH MADDA ABOVE
   "l aH=0x0644 0x0623", // ?? LAM ALEF WITH HAMZA ABOVE
   "l aB=0x0644 0x0625", // ?? LAM ALEF WITH HAMZA BELOW
   "l a=0x0644 0x0627", // ?? LAM ALEF
   //
   // End of shaping part. Autogenerated.
   //

   Gaspar [2003-01-21] clarifies that this section was auto-generated
   by bin/arabickmap.pl, and

   "bin/shape.pl generates a shape.mys shaper map that is responsible
   for Arabic/Syriac shaping. As Yudit is a plain text editor, it
   needs to know the obligatory ligatures, the ones that definitely
   should go into one box. Those four ligatures in the example are
   the obligatory ligatures.

   "Please note: in fact in yudit 2.7.+ you don't need to have it
   because additional characters and diacritics will automatically be
   added to form a ligature, so in fact the aforementioned ligature
   can be entered by simply inputting the components."

   [end of quotation]

   As I interpret this, Arabic kmap files can now be written without
   these four mysterious lines; when the user types laam followed by
   some variety of 'alif letter, the appropriate ligature glyph should
   be displayed automatically.  [This section subject to correction.]


Generic .mys Source Text-Conversion Files [for the future]

   [This section needs to be reviewed and expanded.]

   This document describes the format for .kmap files, which are
   converted into .my files.

   The generic .mys source files provide a few more features than the
   standard .kmap files, and the .mys format will someday be
   recommended as a source format for new kmap files.

   The only documentation currently available for .mys files is in the
   Yudit download:

   http://www.yudit.org/download/yudit-2.7.2/mytool/mys/example.mys

   Better documentation will be required before the average user can
   understand and use .mys files.

Gaspar Sinai <gsinai@yudit.org> Tokyo 2001-01-11
Edited and augmented: ken.beesley@xrce.xerox.com  2003-02-06