Diacritical marks and special charaters.


Subject: Diacritical marks and special charaters.
From: James Silverton (jim.silverton@erols.com)
Date: Tue Aug 01 2000 - 13:02:25 CDT


There has been some discussion about currency symbols and letters with
diacritical marks etc. I admit I had forgotten the information in The
Linux keyboard and console HOWTO by Andries Brouwer, aeb@cwi.nl v2.8, 25
February 1998. I will add the relevant passage (I hope) but, like me,
reading the whole thing is useful.

"8.5. Composing symbols

  A symbol may be constructed using several keystrokes.

  o LeftAlt-press, followed by a decimal number typed on the keypad,
     followed by LeftAlt-release, yields the symbol with code given by
     this number. (In Unicode mode this same mechanism, but then with 4
     hexadecimal digits, may be used to define a Unicode symbol.)

  o A dead diacritic followed by a symbol, yields that symbol adorned
     with that diacritic. If the combination is undefined, both keys are
     taken separately. Which keys are dead diacritics is user-settable;
     none is by default. Five (since 2.0.25 six) dead diacritics can be
     defined (using loadkeys(1)): dead_grave, dead_acute,
     dead_circumflex, dead_tilde, dead_diaeresis (and dead_cedilla).
     Precisely what this adorning means is also user-settable: dead-
     diacritic, symbol is equivalent to Compose + diacritic + symbol.
                    
-- o Compose followed by two symbols yields a combination symbol.
     These combinations are user-settable. Today there are 68
combinations
     defined by default; you can see them by saying "dumpkeys | grep
     compose".

  o Then there are `Sticky' modifier keys (since 1.3.33). For example,
     one can type ^C as SControl, C and Ctrl-Alt-BackSpace as SControl,
     SAlt, BackSpace.

  Note that there are at least three such composition mechanisms:

  1. The Linux keyboard driver mechanism, used in conjunction with
     loadkeys.

  2. The X mechanism - see X386keybd(1), later XFree86kbd(1). Under
     X11R6: edit /usr/X11R6/lib/X11/locale/iso8859-1/Compose.

     See also Andrew D. Balsa's comments at
     http://wauug.erols.com/~balsa/linux/deadkeys/index.html.

  3. The emacs mechanism obtained by loading "iso-insert.el" or calling
     `iso-accents-mode'.
     For X the order of the two symbols is arbitrary: both Compose-,-c
     and Compose-c-, yield a c-cedilla; for Linux and emacs only the
     former sequence works by default. For X the list of compose
     combinations is fixed. Linux and emacs are flexible. The three
     default lists are somewhat similar, but the details are different"

Jim

-- 
James V. Silverton
Potomac, Maryland



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