[links-list] Display of SGML Greek characters

Steve White swhite at zipcon.net
Sun Aug 11 22:30:31 PDT 2002


This week I have written about the way that Links displays Greek
characters.  These characters are meant to display individual
Greek letters in mathematical and other technical documents.

Links, unfortunately, transliterates them into the Latin
equivalents, thus rendering them useless.

I proposed a solution, but it didn't work.  The idea was simply to
change the display of those characters to a textual representation
of the name of the character.  To do this, I tried modifying
character table files.

Character mapping in Links works like this.  It first maps each
SGML entity to a UTF-8 character.  The UTF-8 character is assigned
a 7-bit character string for display.

As it is, Links assigns the Greek SGML characters to the Unicode
characters for the Greek alphabet.  This is reasonable for a
browser that is capable of rendering the glyphs for Greek
characters distinctly from Latin ones.  But Links can't typically
do that.

By itself, this shouldn't have been a problem.  Unicode provides a
separate character range (1D400-1D7FF) for Greek Mathematical
symbols.  It should have been possible to map the SGML entities to
these Unicode characters, then specify 7-bit display strings for
those characters.

Those Greek Mathematical Unicode characters require 32-bit
representations.

Internally, Links must make some use of multi-byte UTF-8, because
one sees reasonable display of pages using 8-bit character
encodings.  It takes a 16-bit Unicode character to do that.

There isn't anything obvious in the code that would prohibit
it from using Unicode in the 32-bit range, but all attempts
to modify the codepage files to represent these characters
have failed.

I'm disappointed, but not thrilled at the prospect of a huge
amount of hacking to fix this one problem.

Perhaps one of you knows the code well enough to say whether the
problem is tractable.   Or maybe there's another solution I didn't
think of.  Or maybe it just doesn't matter that much.


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