From: Kenneth Whistler (kenw@sybase.com)
Date: Mon Aug 11 2003 - 15:57:11 EDT
Kent asked:
> How should a freestanding double diacritic be encoded (for purposes of
> meta-discussions, and the like): <SPACE, dbl diacritic> or <SPACE, dbl
> diacritic, SPACE>?
It *could* be represented as <SPACE, dbl_diacritic, SPACE>, of course,
or for that matter <SPACE, dbl_diacritic, TAB>, or other possibilities.
The combining character sequence, in either case, is the
<SPACE, dbl_diacritic> sequence.
But it *should* be represented by something visually more
meaningful, such as <U+25CC, dbl_diacritic, U+25CC>, which is
how the standard itself tends to represent it when needing
to engage in a meta-discussion. The whole point of a double
diacritic is its graphic application to two base characters,
which point is lost in the discussion if you don't show a
graphic base when displaying the character in isolation.
> How should combining characters (spacing as well
> as non-spacing) that are not vertically centered *roughly* be displayed,
> e.g. <SPACE, right-side combining character>, should that *roughly*
> be displayed with or without a typographic void to the left of it?
It's up to the application. And again, I would say that if this
level of detail is a concern to the person originating the text,
then the better convention is to represent the combining character
on a *visible* generic base.
> So
> if I want a space (though not an overgrown one), should one use
> <SPACE, SPACE, right-side combining character>? Or even <SPACE,
> ZWSP, SPACE, right-side combining character>, to prevent "space
> collapse".
> And similarly for left-side combining characters. Likewise for defective
> combining sequences. If I want a visible pseudo-base, a dotted ring, or
> an
> underline, the answers are fairly clear, using a suitable character as a
> base.
Exactly. Which is why you should use such conventions if you
care about the placement in this detail.
Otherwise, you up-level and make use of whatever mechanisms a
typesetting application makes available for individual adjustment
of the placement of glyphs.
--Ken
> But not for the cases above. I don't think that should entirely up
> to each font (maker), without any recommendation. (A "should" rather
> than a "shall" is quite sufficient.)
>
> /kent k
>
>
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