Missing DEC VT100 graphics characters

From: Markus Kuhn (Markus.Kuhn@cl.cam.ac.uk)
Date: Fri Sep 25 1998 - 06:24:58 EDT


The X11 font

  -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso8859-1

which I am currently extending to Unicode contains in the C0 range
a number of characters that were also available on DEC VT100 terminals.
I assume xterm uses them to emulate the full VT100 functionality,
which includes a simple blockgraphics capability.

Unfortunately, there are four DEC VT100 block graphics characters that
have apparently no Unicode equivalents. They are each a thin horizontal
line at different heights. H. Peter Anvin <hpa@zytor.com> wrote in the
Linux Kernel documentation (/usr/src/linux/Documentation/unicode.txt):

  In addition, the following characters not present in Unicode 1.1.4 (at
  least, I have not found them!) have been defined; these are used by
  the DEC VT graphics map:

  U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1
  U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3
  U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7
  U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9

  The DEC VT220 uses a 6x10 character matrix, and these characters form
  a smooth progression in the DEC VT graphics character set. I have
  omitted the scan 5 line, since it is also used as a block-graphics
  character, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL.
  However, I left U+F802 blank should the need arise.

It might be nice to have equivalents for those in Unicode as well
(probably in the U+259X range). Have they just been forgotten or was
there a deliberate decision not to include them?

Markus

-- 
Markus G. Kuhn, Security Group, Computer Lab, Cambridge University, UK
email: mkuhn at acm.org,  home page: <http://www.cl.cam.ac.uk/~mgk25/>



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