[XeTeX] Fontspec and SBL Hebrew: Possible Bug?

[David Purton]

Hi,

Just wondering if this is a possible bug:

I was looking through the SBL Hebrew manual
(http://www.sbl-site.org/Fonts/SBLHebrewUserManual1.5x.pdf) and noticed
that one of the tricky combinations mentioned in the manual is not
rendered correctly. The particular character in question is the alef on
page 7 of the manual. The SBL Hebrew font is available from
http://www.sbl-site.org/Fonts/SBL_Hbrw.ttf

No combinations I entered gave the correct rendering. Looking at the
font, it looks like there are some unmapped glyphs designed to cater for
this and similar cases. Initially I wondered if the ZWJ was a kludge,
but it does seem to appear in at least some copies of the WLC codex
online. Others use the same character ordering, but without the ZWJ.

My file versions:

This is XeTeX, Version 3.1415926-2.2-0.9995.2 (TeX Live 2009/Debian)
xltxtra: 2009/09/02 v0.5
xunicode: 2008/02/08 v0.91
fontspec: 2008/08/09 v1.18
bidi: v1.1.1, <commit 54>, 2010/07/25


Minimal sample file showing various character orderings possible,
incuding the one with the ZWJ mentioned in the manual.


\documentclass{article}
\usepackage{xltxtra}
\usepackage{bidi}
\newfontfamily\hebrewfont[Script=Hebrew,Contextuals=Alternate,Ligatures=Required]{SBL Hebrew}
\begin{document}
\hebrewfont\setRL
אֲ‍ֽ֭\quad % alef + hataf patah + ZWJ + meteg + dehi (From SBL Hebrew manual)
אֲֽ֭\quad % alef + hataf patah + meteg + dehi
אֲֽ֭\quad % alef + hataf patah + dehi + meteg
אֲֽ֭\quad % alef + meteg + hataf patah + dehi
אֲֽ֭\quad % alef + meteg + dehi + hataf patah
אֲֽ֭\quad % alef + dehi + hataf patah + meteg
אֲֽ֭      % alef + dehi + meteg + hataf + meteg
\end{document}


Questions:

Is there a fontspec option I am missing to enable correct rendering in
this case?

Can others confirm that this is a problem (in case some of my files are
too old)?

Any comments on how XeLaTeX/fontspec should behave? It would make sense
to me for at least the first two options in the minimal file above to
render correctly, since I do not understand why the ZWJ would be
necessary other than as a kludge... but I am very ignorant, so they may
be a good reason. Other parts of the SBL Hebrew manual talk about the
font being able to render correctly pointing and cantilation in any
order. However, I don't understand how and when normalisation should
occur.


cheers

David

-- 
David Purton
dcpurton at marshwiggle.net
 
For the eyes of the LORD range throughout the earth to
strengthen those whose hearts are fully committed to him.
                                 2 Chronicles 16:9a
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