Rule 1:

Root: 

Root Element is the parent of all other nodes.

Example:

<root>   <First child>     <First sub child>.…</First sub child>     <Second sub child>.…</Second sub child> </First child> </root>

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Rule 2:

XML Pro log:

XML prolog is optional. If XML exists then  XML must come first in the document.

Example:

<?xml version=”1.0″ encoding=”UTF-8“?>

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Rule 3:

Case Sensitivity:

XML tags are case sensitive.

Example:

<author> sameed </author> <AUTHOR> sameed <AUTHOR>

In this example both tags representing different tags.

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Rule 4:

Attributes values must be qouted.

Example:

Wrong Practice	Right Practice
<book date=12/11/2007>   <title>Book On XML</title> </book>	<book date=“12/11/2007“>   <title>Book On XML</title> </book>

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Rule 5:

Comment:

Comment are used to give some opinion for better understanding.

Example:

< ! −− this is comment − − >

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Rule 6:

Starting and closing of tags:

• Every tag should have starting and ending.
• For example <author> is the starting of author tag and </author> is the closing of the author tag.
• Early starting tag should be late closed and late started tag should be early close. Example is shown in the diagram below.

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