Re: [emacs-bidi] explicit formatting codes in visual-order text

[Eli Zaretskii]

On Mon, 12 Nov 2001, Alex Schroeder wrote:

> > As for explicit formatting codes in visual-order text, I don't think
> > there is such a thing.  (If someone have seen this, please speak
> > up.)  UAX#9 clearly says that formatting codes are either removed or
> > ignored when reordering from logical to visual.
> 
> Yes, so it says.  I think this means that an implementation which
> leaves the formatting codes as zero-width characters in the text is
> still conformant.

Of course!  Emacs will be one such implementation ;-).  The current
design calls for retaining the formatting codes in the buffer, so that
we could display them in some way if the user wants that.  However,
normally, they will not be displayed (we need to make some change in
the display code to make this possible).

>  Thus:
> 
>   this is a <RLO>fox<PDF>.
> 
> Is displayed as:
> 
>   this is a xof.

Yes.

> If you copy the text into a clipboard, however, you may still find
> them in the output:
> 
>   this is a <RLO>xof<PDF>.

No!  Copying into the clipboard, if it requires a visual-order string,
will remove the formatting codes.  We cannot assume that a program
which doesn't support bidi (and thus needs a visual-order text) can
cope with bidirectional formatting codes.