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   RE: [xml-dev] What A Document Means

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Hello Peter!

Many thanks for your answer.

That is the direction I thought they might be headed in with that, 
but without a reference, I wasn't sure.   So it is an infoset.  That 
is a bit vague and doesn't quite tell us why it is an expensive 
approach, or precisely how it determines a document's "meaning" 
except insofar as information items are grouped.   In other words, 
we can use the infoset to describe it's meaning as a well-formed 
document (as document is defined therein), but not the meaning 
of the content.    If that is the scope of the authors of the the paper's 
intent, that's fine.  In short, they have defined the "meaning" of 
the document to the system, not the meaning of the document 
to any possible set of endpoints where these endpoints are 
automated or human processes.

I am nonplussed by the definition of a document in terms of the 
system features (MIME types) because that seems to be a reasonable 
way to scope the abstraction.

You are right about the significance of the last item.  It reveals 
a flaw.  The "meaning" of the "document" is not the same to 
all parts of the system.   This has been pointed out before as 
a flaw in the current XML framework specifications.


-----Original Message-----
From: Peter V. Mikhalenko [mailto:xml-dev@sigent.ru]

Hello, Len!
You wrote to <xml-dev@lists.xml.org> on Mon, 1 Apr 2002 09:50:56 -0600 :

 BCL> In http://www.w3.org/2001/tag/doc/docmeaning.html
 BCL> "The document forms a complete information set. Although expensive
 BCL> in the general case, it's not entirely unreasonable to imagine
 BCL> applications that examine an entire information set."
 BCL> Can someone explain this?  What is an "information set" and how
 BCL> does  one determine "completeness" for two ends of a single
 BCL> transaction or communication?
 BCL> len

It seems that the authors use the term "information set" in the meaning of
the highest-level document type abstraction; as the XML Information Set
Recommendation (http://www.w3.org/TR/xml-infoset/) says:

"An XML document has an information set if it is well-formed and satisfies
the namespace constraints described below. There is no requirement for an
XML document to be valid in order to have an information set.
Information sets may be created by methods (not described in this
specification) other than parsing an XML document.

An XML document's information set consists of a number of information items;
the information set for any well-formed XML document will contain at least a
document information item and several others. An information item is an
abstract description of some part of an XML document: each information item
has a set of associated named properties. In this specification, the
property names are shown in square brackets, [thus].

The terms "information set" and "information item" are similar in meaning to
the generic terms "tree" and "node", as they are used in computing. However,
the former terms are used in this specification to reduce possible confusion
with other specific data models. Information items do not map one-to-one
with the nodes of the DOM or the "tree" and "nodes" of the XPath data

The last piece is the most significant, I think.


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