XML Information Set

Source: Wikipedia, the free encyclopedia.

XML Information Set (XML Infoset) is a

well-formed XML document

An XML document has an information set if it is

well-formed and satisfies the namespace constraints. There is no requirement for an XML document to be valid
in order to have an information set.

An information set can contain up to eleven different types of information items:

  1. The Document Information Item (always present)
  2. Element Information Items
  3. Attribute Information Items
  4. Processing Instruction Information Items
  5. Unexpanded Entity Reference Information Items
  6. Character Information Items
  7. Comment Information Items
  8. The Document Type Declaration Information Item
  9. Unparsed Entity Information Items
  10. Notation Information Items
  11. Namespace Information Items

XML was initially developed without a formal definition of its infoset. This was only formalised by later work beginning in 1999, first published as a separate W3C Working Draft at the end of December that year.[2] Infoset recommendation Second Edition was adopted on 4 February, 2004.[3] If a 2.0 version of the XML standard is ever published, it is likely that this would absorb the Infoset recommendation as an integral part of that standard.

Infoset augmentation

Infoset augmentation or infoset modification refers to the process of modifying the infoset during

. [4]

Infoset augmentation is somewhat controversial, with claims that it is a violation of modularity and tends to cause interoperability problems, since applications get different information depending on whether or not validation has been performed. [5]

Infoset augmentation is supported by XML Schema but not RELAX NG.


Typically, XML Information Set is serialized as XML.[6] There are also serialization formats for Binary XML, CSV,[7] and JSON.[8]

See also

XML Information Set instances:


  1. ^ W3C XML Infoset
  2. ^ "XML Information Set" (Working Draft ed.). W3C. 20 December 1999.
  3. ^ "XML Information Set" (Second ed.). W3C. 4 February 2004.
  4. ^ XML Schema 1.1 Part 1: Structures
  5. James Clark
    , 4 Jun 2002
  6. ^ "Extensible Markup Language (XML)". W3C. Retrieved 9 October 2014.
  7. ^ XmlCsvReader Implementation
  8. ^ Apache CXF JSON Support

External links