Re: [css-writing-modes] Propose to weaken upright rendering of horizontal-only scripts

Hi Jonathan, thank you for your reply.

On Wed, Apr 29, 2015 at 5:40 PM, Jonathan Kew <jfkthame@gmail.com> wrote:

> On 28/4/15 19:02, Koji Ishii wrote:
>
>> I’d like to propose to weaken spec words when rendering
>> horizontal-only scripts in upright.
>>
>> One in text-orientation: upright, the proposed change is from:
>>
> >   characters from horizontal-only scripts are rendered upright
>
>> to:
>>   characters from horizontal-only scripts should be rendered upright
>>
>
> I don't think this should be weakened to a "should", as this would allow
> an implementation to ignore the 'upright' value and render Latin (etc)
> characters as if it were 'mixed' or 'sideways-right'. We shouldn't leave
> room for that to be claimed as a conforming implementation of
> text-orientation:upright.


I don't think "should" allows such an arbitrary choice, as far as I read
the RFC[1]:

3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.

If we end up, for instance, one character of a script unable to find how to
render in upright vertical flow and unable to find single use case in the
real world, that shouldn't prevent the spec to go on the REC track, should
it?

Then in the definition of “upright characters”[2], from:
>>
> >   characters from horizontal cursive scripts (such as Arabic) are
> >   shaped in their isolated forms when typeset upright
> > to:
> >   characters from horizontal cursive scripts (such as Arabic) should
> >   be shaped in their isolated forms when typeset upright
> > or we could be more descriptive how we’d like to weaken.
>
> Again, I'd prefer not to weaken in this way; I think it's clear that
> cursive horizontal scripts, when typeset in vertical upright mode,
> should use isolated forms rather than their normal (horizontal) cursive
> joining. (Firefox Nightly currently gets this wrong, but should be fixed
> very shortly.)
>
> What's less clear, IMO, is how to handle the complex Indic scripts where
> reordering and clustering behavior is involved.


I was mistakenly classified complex indic scripts as part of "cursive" in
the spec definition, sorry about that.


> The motivation is that I know little about if every single
>> horizontal-only script can really render upright with this
>> definition. I know there are people who knows it better than me, but
>> a discussion of Jonathan and Behdad[3] indicated me that there are
>> more we need to study, and I’m afraid to define it normatively with
>> our current knowledge.
>>
>
> I agree there are gaps in our knowledge of how best to render some scripts
> in this mode, but rather than weakening the current spec text, which I
> think is OK as far as it goes, perhaps we should just have a note that the
> behavior of complex scripts such as Indic and SE Asian in vertical upright
> is not clearly defined yet.


That kind of note works for me. However, I still wonder, "must render
upright" and "behavior is not clearly defined yet" look contradict to each
other, no? Isn't RFC "should" the word to apply such cases?

I'm fine with other words stronger than SHOULD (such as MAY WISH TO[2], we
used this for Tr), but MUST does not look right to me.

[1] http://www.ipa.go.jp/security/rfc/RFC2119EN.html#3
[2] https://tools.ietf.org/html/rfc6919#section-6

/koji