Linux HTML mail agent with RTL and LTR paragraph explicit support

[Eli Zaretskii]

> Date: Mon, 25 Jun 2012 08:06:14 +0300
> From: Shachar Shemesh <shachar at shemesh.biz>
> Cc: linux-il at cs.huji.ac.il
> 
> What the standard[1] suggests, but does not
> require, is the use of the first strong directional character in the
> paragraph.

You are wrong, it does require that.  See below.

>     the standard says nothing about what to do with a paragraph with
>     no strong directional character at all.

Not true:

  P3. If a character is found in P2 and it is of type AL or R, then
      set the paragraph embedding level to one; otherwise, set it to
      zero.

The last part means that a paragraph without any strong directional
character has L2R base direction.

>  2. This suggestion is non-normative. The standard explicitly states
>     that a "higher level protocol" can be used to determine this property.

That is a strange interpretation of the UBA's language.  The higher
level protocols clause is clearly meant for _improving_ the display
by tailoring it to the needs of the application and its users.  It
certainly isn't meant to allow bypassing the determination of the
paragraph direction altogether; that simply makes no sense.

>  4. The only standard way to provide paragraph directionality in email
>     is by sending it as HTML

I think this assertion is rather extreme.  Using a bidi-aware mail
client, you can certainly do that in plain text as well.  Please don't
forget that Unicode in general and the UBA in particular are first and
foremost about plain text.  Marked-up text, such as HTML, has other
means to specify directionality, and thus doesn't mean the bidi
formatting control characters at all.  It only needs the implicit
levels and the corresponding reordering.

> most of the world uses various MS based email
> readers. Those don't do it, and they do not violate any standard by not
> doing it. As a result, if you want your email to be legible by any
> recipient, HTML mail is the way to go if you are writing in Hebrew.

This is a strange thing to read in a forum dedicated to advancing
GNU/Linux systems.  Since when do we in the Free Software movement bow
to badly implemented standards in MS software and take example from
there?

Btw, Outlook does support directional control characters; e.g., you
can use LRO..PDF to get a string of Hebrew characters displayed in
strict logical order.  It's just that it doesn't implement the
paragraph direction part of the UBA, no doubt because the
corresponding Windows text widget doesn't (I see the same problem in
Notepad).

> No. I am referring to all those who complain so violently when HTML mail
> is sent to the list.

I'm not going to complain, certainly not "violently", but please note
that using HTML does have its disadvantages.  E.g., look at one your
message as archived by the server for this forum:

  http://www.mail-archive.com/linux-il@cs.huji.ac.il/msg63031.html

All your careful formatting is gone, and the Hebrew text reads
awkwardly (at least in my Mozilla Firefox v13.0.1).

So I think using plain text and insisting on MUAs to support the UBA
does have its merits.  At least in Emacs 24, which I use for email (as
well as for many other things), I see no problems with that.