Re: [docbook] Error processing FO output from docbook-xsl

[Daniel Veillard <veillard at redhat dot com>]

On Wed, Oct 08, 2003 at 03:16:05PM -0400, Jeff Beal wrote:
> I can see where the confusion comes from.  Why does the definition of the
> PITarget exclude PITargets that match (('X'|'x')('M'|'m')('L'|'l')) if that
> is already implicit from the use of the 'Name' production?  (That's a
> rhetorical question -- no need to answer.)

  It's not rethorical, it's very practical, there are good reasons for
both rules, and since there is some confusion around this issue it's better
to try to give an explanation, it's not evilness it's just pure 
engineering.
  "xml" prefix in name is reserved, it does not lead to an error. You get
a warning from xmllint, the parsing does not fail, it still processes
the document. On the other hand having <?xml bad pi?> is a well formedness
error:

paphio:~/XML -> cat tst.xml
<!-- something before -->
<?xml bad pi?>
<doc/>
 
paphio:~/XML -> xmllint tst.xml
tst.xml:2: parser error : XML declaration allowed only at the start of the document
<?xml bad pi?>
     ^
paphio:~/XML -> cat tst2.xml
<!-- something before -->
<?xmlspy bad pi?>
<doc/>
 
paphio:~/XML -> xmllint tst2.xml
tst2.xml:2: parser warning : xmlParsePITarget: invalid name prefix 'xml'
<?xmlspy bad pi?>
        ^
<?xml version="1.0"?>
<!-- something before -->
<?xmlspy bad pi?>
<doc/>
paphio:~/XML ->

  In the second case it's an use of a reserved word, xmllint doesn't
handle what could be an unknown extension to XML, so you just get
a warning. In the first case, it's a well formedness error and libxml2
doesn't generate a tree for the document.
  I suppose the use of "xml" case insensitive for PI names has been
made a Well Formedness error to be 100% sure that they won't be mistaken
for XML Declarations (the optional <?xml...?> construct at the beginning
of an XML document).

Daniel

-- 
Daniel Veillard      | Red Hat Network https://rhn.redhat.com/
veillard@redhat.com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
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