[techspace] Re: Questions related to XML

Falk, Alexander falk at icon.at
Fri Jan 7 08:20:11 GMT 2000

ad 1)
yes, the XML grammar is specified in EBNF (extended backus naur form) in the
original XML 1.0 specification (
<http://www.w3.org/TR/1998/REC-xml-19980210#sec-notation> ), but the
individual lines of the EBNF are scattered through the specs. For a more
condensed version, please download our XML editor XML Spy (
http://www.xmlspy.com <http://www.xmlspy.com> ) which uses an external EBNF
file to drive its parser, so you can simply take the file "gra_xml.txt" as a
starting point after installing our software.
ad 2)
XML is defined as a Unicode compliant document, so the XML "keywords" (or
more correctly: element names) can come from almost any other character set.
If you are interested, I have collected numerous international XML example
documents that contain korean, japanes, russian, thai, etc. element names.
ad 3)
two different answers:
a) if your document does not refer to a DOCTYPE (either internally or to an
external DTD file) and it is well-formed, then it is also considered valid
b) if you include a DOCTYPE that defines only <!ENTITY ...> rules, but not
<!ELEMENT ...> constrains, then your document will also be not imposing any
restrictions and be valid
ad 4)
no, a document can only refer to one external DTD file. However, an external
DTD can then include several other "partial" DTD files, so you can easily
separate your document type into smaller chunks and put them together
individually for each XML file depending on the particular needs. The key is
to use "external entities" in the DTD that are then resolved by including an
external file.
ad 5)
yes, you can also define DOCTYPEs that declare elements recursively. This is
OK and is in fact also used in many popular DTDs (e.g. XHTML 1.0)
Alexander Falk

... Icon Informations-Systeme GmbH
... makers of the XML Spy editor ( http://www.xmlspy.com
<http://www.xmlspy.com> )
... President, CEO 
... http://www.icon.at/falk <http://www.icon.at/falk>  

-----Original Message-----
From: V P Krishnan [mailto:vilayanur.krishnan at intelligroup.com]
Sent: Friday, January 07, 2000 2:41 AM
To: xml-dev at ic.ac.uk
Subject: FW: [techspace] Re: Questions related to XML

We had the following questions that came up during our internal discussions.
Would appreciate anyone taking time for an answer to Q1 through Q4. 
-----Original Message-----
From: Muthu Kuttalingam [mailto:muthu.kuttalingam at intelligroup.com] 
Sent: Thursday, January 06, 2000 6:30 PM
To: techspace at egroups.com
Subject: [techspace] Re: Questions related to XML

The following XML is well-formed according to XML Spy 2.5 an XML editor. So
I guess, the answer to question number 5 is yes.

<?xml version="1.0" encoding="UTF-8"?>



        <test>This is a test</test>



-----Original Message-----
From: kaustubh.kunte [mailto:kaustubh.kunte at intelligroup.com]
Sent: Wednesday, January 05, 2000 9:46 PM
To: techspace at egroups.com
Subject: [techspace] Questions related to XML

Here are the list of questions which came up during XML discussion. If you
find an answer to any of these,
please do share it with the techspace community.
1. Can XML grammar be represented in Backus Naur format ( BNF ) .
2. Should XML keywords be always represented in a specific ASCII format or
can you use different character set .
3. How to define a NULL DTD. ie a DTD which specifies no constraints. This
questions came up because a DTD 
is required for a document to be valid. So can we define a NULL DTD which
will effectively treat all well formed XML documents
as valid documents.
4.Is there a way of declaring multiple external dtd's in the document type
declaration ?
5. Can a child element have same name as the parent element ?
Jai XML !!

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