Re: Use of < and > in XML

From:

ram@zedat.fu-berlin.de (Stefan Ram)

Newsgroups:

comp.lang.java.programmer

Date:

2 Aug 2008 16:15:50 GMT

Message-ID:

<XML-20080802181348@ram.dialup.fu-berlin.de>

Roedy Green <see_website@mindprod.com.invalid> writes:

Is this correct. In garden variety XML you can't have the
characters < and > in your data.

  There is no ?garden variety XML?. There is XML 1.0

http://www.w3.org/TR/2000/REC-xml-20001006.html

  and XML 1.1

http://www.w3.org/TR/xml11/

  . Both do not differ with regard to your question.

You could only have them if you did some voodoo
to define the entities. The Entity definition is part of a
DTD, not he document itself.

  The word ?entity? does have another meaning in XML than you
  believe.

      ?An XML document may consist of one or many storage units.
      These are called entities;?

http://www.w3.org/TR/2000/REC-xml-20001006.html#sec-physical-struct

  For example, the whole XML document is an entity,
  the ?document entity?.

  You can represent ?<? and ?>? in XML as data characters in
  several ways.

  The most direct way is a CDATA section.

      ?<![CDATA[<greeting>Hello, world!</greeting>]]>?

http://www.w3.org/TR/2000/REC-xml-20001006.html#sec-cdata-sect

  Another example would be:

      ?<![CDATA[<greeting>Hello<<<world!</greeting>]]>?

  You can use character references for them:
  ?<? for ?<?, and ?>? for ?>?. See:

http://www.w3.org/TR/2000/REC-xml-20001006.html#sec-references

  You can use entity references for them:
  ?<? for ?<?, and ?>? for ?>?.
  These are entity /references/, not entities. Also see:

http://www.w3.org/TR/2000/REC-xml-20001006.html#sec-references

  Finally, The use of ?>? within data is allowed:

      ?CharData ::= [^<&]* - ([^<&]* ']]>' [^<&]*)?

http://www.w3.org/TR/2000/REC-xml-20001006.html#syntax

  Only ?<? is not CharData. So this is well-formed XML:

      <?xml version="1.0"?><greeting>Hello>>>world!</greeting>