SDD bogus

David Megginson ak117 at
Fri May 8 15:57:54 BST 1998

Paul Prescod writes:

 > Is the standalone document declaration bogus and perhaps dangerous?

Yes and yes.  

The problem, I think, came from the mistaken idea that people
(i.e. desperate Perl hackers) would write custom parsers for each XML
application (like RDF), and that these people would not want to deal
with seemingly difficult problems like external entity resolution.  

In the end, as one might have predicted, there is an impressive range
of free XML processors available in several different programming
languages: someone writing an RDF tool does not need to worry about
the character and entity level of XML at all, and can work with XML
easily through a more abstract interface such as the DOM or SAX.

So, we should let the authors decide -- if an author creates a
document referencing external entities (including an external DTD
subset), then the XML parser should handle them; if the author does
not want to use external entities, then she can simply avoid
referencing any.

As many XML parser writers have shown, resolving external entities is
one of the easiest parts of XML (especially in higher-level languages
like Java or Perl, and, I presume, Python).  Allowing parsers to skip
external entities -- rather than simplifying XML -- ended up making it
much more complicated, and as you point it, the standalone declaration
really doesn't help things.

All the best,


David Megginson                 ak117 at
Microstar Software Ltd.         dmeggins at

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