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From: knuutila@tucos.utu.fi (Timo Knuutila)
Newsgroups: comp.text.tex
Subject: Problem with TeX character codes
Message-ID: <1991Feb7.112203.12456@polaris.utu.fi>
Date: 7 Feb 91 11:22:03 GMT
Sender: news@polaris.utu.fi
Organization: University of Turku, Finland
Lines: 49

Dear TeXackers,

I encountered the following problem when trying to marry TeX, PostScript fonts
and foreign language hyphenation in my TeX-system (SB-TeX, emTeX drivers and
font libraries, dvips54, 386 PC).

I have a scandinavian keyboard with special keys for the accented scandinavian
letters (\"a, \"o, \"A, \"O, \aa, \AA) and I'm trying to map these to the
corresponding PostScript character codes. In what follows, suppose that
x, y, X and Y stand for the characters of a-, o-, A- and O-umlaut,
respectively.

The keyboard codes for the characters, ie. the codes TeX sees at the first
glance, are as follows:

    x: 0x84   y: 0x94   X: 0x8E   Y: 0x99

The easiest way to map these characters to something TeX knows about, would be

    \catcode`\x=\active    \catcode`\y=\active
    \catcode`\X=\active    \catcode`\Y=\active

    \defx{\"a}  \defy{\"o}  \defX{\"A}  \defY{\"O}

but then it would be impossible to hyphenate words containing these characters
(and thus accents). They should be mapped directly to character codes (the
same that are used in the hyphenation patterns) in order to maintain the
hyphenation capability. The corresponding codes in the PostScript font tables
are given below:

    x: 0x99    y: 0x89   X: 0xD2   Y: 0xBE

I made the following macro definitions (after x etc had been declared to be
active characters):

    \defx{^^99}    \defy{^^89}    \defX{^^d2}    \defY{^^be}

The problem is that the `keyboard code' of Y is the same as the PS character
code of x (0x99). Thus, TeX maps x first to Y and then to ^^be, which is
obviously not what I want. However, even if I change the \defx to (11 is the
category code of letter characters)

    \defx{\catcode`^^99=11 ^^99\catcode`^^99=\active}

the result is just the same --- x is mapped to ^^BE. Where have I gone wrong?


        Timo Knuutila
        knuutila@cs.utu.fi