optional ncx attributes treated as required about epubcheck HOT 3 CLOSED

I think it is a valid bug. I have asked Markus (our NCX expert) to confirm this.

I have commited a fix to this issue to the trunk. Both the official NCX DTD[1] 
and
the unoffical DAISY NCX RelaxNG schema [2] indeed declare xml:lang and dir as 
optional.

I successfully tested the change against the sample that hxa7241 referenced, 
however,
suggest that we get an external confirmation before closing this issue.

Note: optional or not, I would strongly suggest that you do make use of 
xml:lang to
the extent possible in the different files of the OPS fileset, as it is central 
for
user agent behavior. In forthcoming versions of NCX and DTBook, xml:lang may 
very
well become required...

/markus

[1]http://www.daisy.org/z3986/2005/ncx-2005-1.dtd
[2]http://daisymfc.svn.sourceforge.net/viewvc/daisymfc/trunk/dmfc/src/org/daisy/
util/xml/catalog/z39862005/ncx-2005-1.rng?view=markup