Re: bidi support for xterm

From: Frank da Cruz (
Date: Mon Aug 16 1999 - 13:20:04 EDT

> I would be glad to know which model is mandated by ISO 6429 and which
> is implemented by Kermit. (We might as well try to ensure that the
> two most popular terminal emulators are compatible.)
Kermit only does what the real terminal does. The VT102-H does very
little indeed beyond supporting Hebrew letters. When the application is
sending Hebrew to the screen, it positions the cursor for each letter.

The VT220-H and higher allow the host to switch screen writing direction,
so the host application can send a stream of Hebrew letters in natural
order and have them displayed RTL. But again, the control is entirely
in the host.

This is why some people call terminals "dumb". Once you start making them
smart enough to wrap words, hyphenate, and handle BIDI on their own, the
host application quickly loses any idea of what the screen looks like,
and then all bets are off.

If xterm is to handle Hebrew or other RTL writing systems, it should do so
in the same way as the terminal it is emulating, because it's a terminal

- Frank

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