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RE: Unnecessary well-formedness constraint

• From: Justin Lipton <justin@s...>
• To: "Xml-Dev (E-mail 2)" <xml-dev@l...>
• Date: Sat, 14 Oct 2000 09:20:40 +1000

Perhaps I'm missing the point on this thread:


Example:
We use the parameter entity extras to either IGNORE or INCLUDE an element in
the DTD.

DTD:
<!-- Highest level construct is bugs. Start with this.  -->
<![ %extras; [
        <!ELEMENT revision (#PCDATA)>
		<!ATTLIST revision version (1|2|3|4) "1">

]]>

<!ELEMENT bugs (bug*)>

	<!ELEMENT bug (reporter, descriptor, resolution)>
		<!ATTLIST bug ID ID #REQUIRED>
		<!ATTLIST bug type (Defect | Functionality_Change|Enhancement | WishList)
"Defect">
	<!ATTLIST bug category (Critical | Major | ASAP | Minor) "Critical">
	<!ATTLIST bug component (Editor | Engine| Conversion | Repository | DTD)
"Editor">
	<!ATTLIST bug status (open|closed|in_progress|on_hold) "open">

	<!ELEMENT reporter (who, date)>
		<!ELEMENT who (#PCDATA)>
		<!ELEMENT date (#PCDATA)>

	<!ELEMENT descriptor (#PCDATA)>
		<!ATTLIST descriptor platform
(Windows95|Windows98|WindowsNT|Windows2000|Linux|Mac|All) "Linux">

	<!ELEMENT resolution (todo, modules, fixer)>
	<!ELEMENT todo (#PCDATA)>
	<!ELEMENT modules (#PCDATA)>
	<!ELEMENT fixer (who, date)>






XML:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE bugs SYSTEM "bugs.dtd" [
        <!ENTITY % extras "IGNORE">
]>

<bugs>
	<bug type="Defect" status="closed" component="Editor" category="Critical"
ID="editor1">

		<reporter>
			<who>JML</who>
			<date>14 Sept 2000</date>
		</reporter>

		<descriptor platform="Windows2000">
		Parsing of internal subspaces is casing problems.
		</descriptor>

		<resolution>
			<todo/>
			<modules>
			DOM liasons?
			</modules>

			<fixer>
				<who>JML</who>
				<date>20000915</date>
			</fixer>

		</resolution>
	</bug>
</bugs>

Our experience so far is that some parsers handle this and some don't -
Xerces seems to like it, XML4J doesn't, XMLSpy doesn't etc.

Is this a valid construct?
According to below (Section 4-1 of XML 1.0 spec)
"Parameter-entity references may only appear in the DTD."

Yours in confusion,
Justin.


-----Original Message-----
From: Martin Gudgin [mailto:marting@d...]
Sent: Friday, 13 October 2000 07:15
To: XML-Dev Mailing list
Subject: Re: Unnecessary well-formedness constraint


> "Elliotte Rusty Harold" wrote
>
> Section 4-1 of the XML 1.0 second edition spec states:
>
>
> Well-Formedness Constraint: In DTD
> Parameter-entity references may only appear in the DTD.
>
>
> The Annotated XML spec notes that:
>
> This constraint is not actually wrong, but it is rather misleading.
> Suppose I have a parameter entity named Fred, then if the string %Fred;
> appears somewhere in the document, outside of the DTD, that's not an
> error as this suggests; it's just the string %Fred;.
>
> So my question is why is this constraint here at all? What is its
> effect? If we removed it form the spec (say in the third edition) would
> this in any way change which document are considered to be well-formed
> or valid? Would removing it give parsers any leeway they don't have now?
> Right now this seems like an unnecessary statement to me.
>

My understanding is that the spec is correct; parameter entity references
cannot appear outside of a DTD, the reason being that outside of a DTD
%Fred; is *not* a reference to a parameter entity, it's just the string
%Fred;. Put another way the % character is only treated specially in the
DTD, it is treated just like any other character when encountered in the XML
part of the document.

Martin Gudgin
DevelopMentor

• References:
  • Re: Unnecessary well-formedness constraint
    • From: Martin Gudgin <marting@d...>

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