[XOM-interest] Problem with "Missing scheme in absolute URI reference"

Elliotte Harold elharo at metalab.unc.edu
Thu Jan 1 12:07:31 EST 2009


Peter Murray-Rust wrote:

> I accept this (reluctantly). Could not XOM parse the standalone="yes" 
> message and so not pass the DTD address to Xerces?). I still don't 
> understand where the error message comes from but it must be somewhere 
> in the DTD structure on the W3C pages. I don't understand why a DTD has 
> to reference a namespaceURI at all and why the error is generated in the 
> way it is. Is Xerces producing a misleading error message? And is the 
> W3C spec in error (it validates on their pages) or does Xerces report a 
> spurious error?

I still have to look at where that error is coming from. I agree it does 
sound misleading.

The problem with standalone='yes' is that there's limited guarantee that 
it's accurate. What is a parser/XOM supposed to do when it hits an 
undeclared entity reference after not reading the DTD?

Also, standalone='yes' actually has a very technical meaning. In 
practice, standalone='yes' is wrong for almost every document with a DTD:

The standalone document declaration MUST have the value "no" if any 
external markup declarations contain declarations of:

     * attributes with default values, if elements to which these 
attributes apply appear in the document without specifications of values 
for these attributes, or
     * entities (other than amp, lt, gt, apos, quot), if references to 
those entities appear in the document, or
     * attributes with tokenized types, where the attribute appears in 
the document with a value such that normalization will produce a 
different value from that which would be produced in the absence of the 
declaration, or
     * element types with element content, if white space occurs 
directly within any instance of those types.

If we were redesigning XML from scratch today, I think the standalone 
document declaration would be one of the first things to go (right after 
the internal DTD subset).

-- 
Elliotte Rusty Harold  elharo at metalab.unc.edu
Refactoring HTML Just Published!
http://www.amazon.com/exec/obidos/ISBN=0321503635/ref=nosim/cafeaulaitA


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