XML Syntax Rules

XML
Syntax Rules

The syntax rules of XML
are very simple and logical. The rules are easy to learn, and easy to use.

1.     All XML Elements Must Have a Closing
Tag

In
XML, it is illegal to omit the closing tag. All elements must have a
closing tag:

<p>This is a paragraph</p> <p>This is another paragraph</p>

 

2.     XML Tags are Case Sensitive

XML tags are case sensitive. The tag <Letter> is
different from the tag <letter>.

3.     XML Elements Must be Properly Nested

In
XML, all elements must be properly nested within each other:

<b><i>This text is bold and italic</i></b>

 

4.     XML Documents Must Have a Root
Element

XML
documents must contain one element that is the parent of all other
elements. This element is called the root element.

<root>   <child>     <subchild>.....</subchild>   </child> </root>

 

5.     XML Attribute Values Must be Quoted

<note date="12/11/2007">

  <to>Tove</to>

  <from>Jani</from>

</note>

6.     Entity References

Some characters have a
special meaning in XML.

If you place a character
like "<" inside an XML element, it will generate an error because
the parser interprets it as the start of a new element.

To
avoid this error, replace the "<" character with an entity
reference:

<message>if salary &lt; 1000 then</message>

There
are 5 predefined entity references in XML:

&lt;	<	less than
&gt;	>	greater than
&amp;	&	ampersand
&apos;	'	apostrophe
&quot;	"	quotation mark

Note: Only the characters "<" and
"&" are strictly illegal in XML. The greater than character is
legal, but it is a good habit to replace it.

 

7.     Comments in XML

The syntax for writing
comments in XML is similar to that of HTML.

<!-- This is a comment
-->

 

8.     White-space is Preserved in XML

HTML
truncates multiple white-space characters to one single white-space:

HTML:	Hello           Tove
Output:	Hello Tove

With
XML, the white-space in a document is not truncated.

 

9.     XML Stores New Line as LF

In Windows applications, a
new line is normally stored as a pair of characters: carriage return (CR) and
line feed (LF). In Unix applications, a new line is normally stored as a LF
character. Macintosh applications also use an LF to store a new line.

XML stores a new line as
LF.

 

hildren:
<title>,< author>, <year>, <price>.

for more info go to : http://www.w3schools.com/xml/