Re: basic XML questions on: non-determism

[Patrick Ohl <Patrick.Ohl@o-h-l.de>]

Hi there,

"Roger L. Costello" wrote:
> [1] It was my understanding that the following is not allowed:
> 
>      <!ELEMENT signature (name | (name, date))>
> 
> because it would require an XML Parser to "look-ahead" when it
> encountered the <name> element to determine which choice was taken.
> 
> I have actually tested this example with xerces and XML Spy.  Both
> parsers accept this.  Are they erroneously accepting this?  Can someone
> please clarify what it means that non-deterministic content models are
> not allowed in XML?

Appendix E in the XML Spec ( http://www.w3.org/TR/REC-xml#determinism )
is Non-Normative. The non-determinism is mostly for SGML compatibility.

So it more a 'should' than a 'must'. In most cases non-deterministic
expressions can easily be translated to detemistic ones. so in your
example:

	<!ELEMENT signature (name, (date)?)>

A good DTD should do it this way.

(I am currently building a XML to Java Data-Binding tool. And it
happened to be a problem to translate ambiguous content models. But
there are algorithms to transform them to unambiguous. Ugh! Just don't
want to implement them...)

Cheers Patrick
begin:vcard 
n:Ohl;Patrick
tel;cell:+49-1708607430
tel;home:+49-89-38859084
tel;work:+49-89-358680-45
x-mozilla-html:FALSE
url:http://www.jNerd.de
adr:;;Ainmillerstr. 6;Munich;;80801;Germany
version:2.1
email;internet:Patrick.Ohl@o-h-l.de
fn:Patrick Ohl
end:vcard