From: Peter Kirk (peterkirk@qaya.org)
Date: Fri Jul 30 2004 - 09:06:29 CDT
There appear to be two errors (not listed in the errata page
http://www.unicode.org/errata/) in Figure 15.2 on page 391 of The
Unicode Standard 4.0, the online version at
http://www.unicode.org/versions/Unicode4.0.0/ch15.pdf.
The fourth and last column of the table appears to be the same as the
third column, except for the header row and the first content row
referring to the fi ligature. But the forms in the second and third rows
seem to be incorrect. (The forms in the fourth row should be the same.)
The fourth column is supposed to indicate the desired rendering of <C1,
ZWJ, C2>. But in the text just before, ZWJ is specified as follows:
> ZWJ requests that glyphs in the highest available category (for the
> given font) be used:
> 1. Unconnected
> 2. Cursively connected
> 3. Ligated
The forms in the fourth column of the figure, for <lam, ZWJ, alef> and
<meem, ZWJ, jeem> are apparently cursively connected forms, but they are
not the ligatures which appear in the first column of the table. The
first column shows that there are ligatures available in the font, and
by the rules for ZWJ these ligatures should be selected by these
sequences. The correct way of selecting the cursively connected but not
ligated forms which are shown is to insert <ZWJ, ZWNJ, ZWJ> as in the
third column. So the forms in the fourth column should be corrected to
be the ligature forms already shown in the first column.
There also seems to be an error in the text just before the figure which
states "In the Arabic examples, the characters on the left side are in
visual order already, but have not yet been shaped." In fact they have
been shaped, at least in the second and third rows - no shaping applies
(by default) to the fourth row.
Am I correct that there are errors here?
Ah, now I see the following paragraph. But if this paragraph is intended
to modify the definition of ZWJ already given, it should be part of the
specification, rather than being given after the examples, and
specifically the examples which illustrates it. And this does not
explain the error in the text.
PS to John Hudson: The second row of this figure is an example of how
<C1, C2>, <C1, ZWJ, C2> and <C1, ZWNJ, C2> must have three separate
renderings, something which you told me (on the Hebrew list) was
impossible both conceptually and with current rendering engines.
-- Peter Kirk peter@qaya.org (personal) peterkirk@qaya.org (work) http://www.qaya.org/
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