From: Asmus Freytag (firstname.lastname@example.org)
Date: Fri Mar 30 2007 - 02:53:16 CST
Just because printers in the past grabbed whatever combination worked,
is not a good guidance as to the suitability of using combinations. If
the underlying intent is to create a new 'entity' then the requirement
is to encode that entity. Some entity decompose, but our rules for
decompositions is not merely that a similar visual effect *can* be
produced, but that the elements of the decomposition, when combined,
correctly form the new entity.
Losing sight of this would be to take a big step backwards, to the days
when o-slash, for example, was represented with fallback overstrikes
such as o^H/.
I will not quibble with Ken's analysis that the new entity is not an Up
Tack. An I will not quibble with the fact that the entity is a
modification of a MACRON. I'll take these as read, for the sake of the
following argument. I remain very much unconvinced that the decoration
on that macron is correctly represented by a combining vertical line
above. I can see no convincing evidence in the discussion.
Because of that, I see as viable alternatives either, the encoding of a
character to correspond with the entity as a whole, or the encoding of
the correct modification for the macron. Overall, placement of multiple
combining marks strikes me as a fragile (except in the context of
strong, well supported language-based requirements such as for
Vietnamese, Polytonic Greek and ignoring scripts with so called 'complex
layout' such as Arabic and similar cases for the moment). Because of
this, I think that the best user experience might be generated by
encoding the entity as such.
On 3/29/2007 4:27 PM, Kenneth Whistler wrote:
> Philippe Verdy said:
>> So use: <U+0304, U+030D> (COMBINING MACRON ABOVE, COMBINING VERTICAL LINE
> I agree with Philippe that a sequence of existing diacritics (with
> that being one of the more likely alternatives) would be sufficient
> for simply being able to represent the text in question digitally.
> It would give you a unique representation for the text, distinguished
> from the letters that have only the macrons. With fallback representation,
> using most existing fonts, you'd be able to distinguish the text
> just fine, although the vertical line above wouldn't tend to
> display optimally (connected to the macron). And even that could
> be fixed by simply creating a font with appropriate ligatures for the
> diacritic sequences.
>> There's absolutely no evidence that this is a unique diacritic with
>> distinct semantic.
> This I completely disagree with. The phonetic guides for the
> books in question *are* the evidence for a unique diacritic
> with a distinct semantic. The text even spells out exactly
> what that "semantic" is for the system in question. That
> the semantic is not well-founded from either a modern
> phonological point of view or as a symbol for an English-based
> pronunciation guide, has no bearing on the distinctness of
> the written mark as a symbol, as a unit of written text
> representation, and hence as a valid candidate for being
> encoded as a character.
> The fact that a symbol has a graphological history as a diacritic
> modification of another preexisting symbol does not disqualify
> the result from being treated as a character in its own right.
> In this particular instance, I think a case can be made
> for either approach. Encode the diacritic-modified macron
> simply with a sequence of the existing encoded macron and
> another existing mark; or encode a new combining mark for
> the diacritic-modified macron (and do not canonically
> decompose the resulting encoded character).
>> And the second diacritic used on top of the macron is not
>> really clear.
> Agreed. I think the printer simply grabbed "apostrophe" punches
> from a poor quality set of cases for what was already a
> hacked up set of metal type, where the macrons, breves and
> such on letters had been created by a similar process in
> the first place. The overpunched diacritics sometimes look
> like vertical lines, sometimes tapered vertical lines, sometimes
> a bit more like acutes, and sometimes more like comma-shaped
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