Why do the Hebrew Alphabetic Presentation Forms Exist

[Mark E. Shoulson]

On 6/4/20 12:15 PM, Richard Wordingham via Unicode wrote:
> On Thu, 4 Jun 2020 08:28:08 -0400
> "Mark E. Shoulson via Unicode" <unicode at unicode.org> wrote:
>
>> On 6/3/20 11:44 PM, Sławomir Osipiuk via Unicode wrote:
>>> A variation selector seems like a good choice here. There should be
>>> a way to request from the rendering engine a specific variant of
>>> the “same” character. There is precedent for that in many other
>>> characters/languages.
>> This isn't a matter for a variation selector.  This is purely a
>> *scribal* or *presentation* alternation.  It has as much relevance to
>> the content of the text as choice of font.  This is a matter for a
>> stylistic alternate in the font tables.  This is *exactly* what those
>> are for!
> That wasn't obvious to whoever first implemented them in MS Word.  The
> feature settings for a font applied throughout the document!

Ah.  I'd been seeing it in LibreOffice and other places, where you can 
twiddle the settings on individual spans, and didn't realize that 
originally these things were expected to be document-wide.  Thank you 
for correcting me.  Would you say, though, that while it may not be what 
they were originally meant for, that this use fits very well into how 
they can be and are used today?

>    There's
> also a problem that application writers think one needs a friendly
> interface expressed in layman's terms, whereas a fix like this is
> quite likely to be described in the documentation as 'Set feature cv05
> to 6 for lamedh to be bent'. It took ages to get OpenType features
> supported in LibreOffice, even though they'd already implemented
> Graphite features.
Yeah, user interface is a hassle at all levels, and complicated things 
are going to have complicated interfaces.
> Now, it has been pointed out elsewhere that for best effects, shaping
> should apply to whole paragraphs.  Fortunately, applying to whole words
> is usually good enough.  However, what if a word has two lamedhs, and
> only is to be bent?  Are mere word-processors now up to handling that
> and processing the whole word as a whole, even though different parts
> have different feature settings?

Yes, what I had been envisioning would indeed involve setting the use of 
font-features on small (one-character) spans in the middle of words, and 
I didn't consider how well word-processors can handle such a thing, and 
I don't really know.  What about things like 'swsh' tables for swash 
effects?  Are those applied to a whole word (paragraph?) at a time, but 
the table itself only affects the final letters of words?  Or do you 
have to apply it to each individual letter that you would see swashed?  
If the latter, it's a lot like what I'm thinking about in this case.

~mark