Validating Entities (was Re: XML Torture Test: Parsers Fail)

David Megginson david at
Wed Apr 7 19:06:19 BST 1999

Richard L. Goerwitz writes:

 > All the spec says is that validity depends on entities matching
 > certain productions in the grammar.

No, XML 1.0 says that *well-formedness* depends on entities matching
certain productions in the grammar.  The spec contains no concept of
validity for individual entities.  Here's what it does say:

(from 2.1 Well-Formed XML Documents)

  A textual object is a well-formed XML document if: 
  1.Taken as a whole, it matches the production labeled document. 
  2.It meets all the well-formedness constraints given in this specification. 
  3.Each of the parsed entities which is referenced directly or
    indirectly within the document is well-formed. 

(from 2.8 Prolog and Document Type Declaration)

  An XML document is valid if it has an associated document type
  declaration and if the document complies with the constraints
  expressed in it.

(from 4. Physical Structures)

  An XML document may consist of one or many storage units. These are
  called entities; they all have content and are all (except for the
  document entity, see below, and the external DTD subset) identified
  by name. Each XML document has one entity called the document
  entity, which serves as the starting point for the XML processor and
  may contain the whole document.

I don't think that there's much room for ambiguity here: 2.1 defines
what a well-formed document is, 2.8 further defines clearly what it
means for a well-formed document to be valid, and 4 makes it clear
that multiple entities still count as a single document.

All the best,


David Megginson                 david at

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