This document outlines the basic rules and structure of XML including: 1) All XML elements must have a closing tag and be properly nested. 2) XML documents must have a single root element and attribute values must be quoted. 3) Special characters like < and & need to be written as entity references like &lt; and &amp; for XML to be valid.

1. XML STRUCTURE
SARASWATHI RAMALINGAM
SRI AKILANDESWARI WOMENS COLLEGE

2. XML STRUCTURE
• All XML Elements Must Have a
Closing Tag
• XML requires all tags to be closed
<markup>This is not valid XML
<markup>Since there is no closing tag

3. XML STRUCTURE
• XML Tags Are Case Sensitive
• <Markup>These two tags are very
different</markup>

4. XML STRUCTURE
• All XML Elements Must Have Proper
Nesting
<oxygen><nitrogen>These tags are
improperly
nested</oxygen></nitrogen>

5. XML STRUCTURE
• All XML Documents
Must Contain a Single
Root Element
<?xml version=”1.0”?>
<Father>
<Son>
<Daughter>
</Daughter>
</Son>
</Father>
<Mother>
<Son>
<Daughter>
</Daughter>
</Son>

6. XML STRUCTURE
• Attribute Values Must Be Quoted
<?xml version=1.0?>
<shirt>
<price currency=USD>14.99</price>
</shirt>

7. XML STRUCTURE
• Attributes May Only Appear Once in
the Same Start Tag
<shirt size=”large” size=”small”>Zippy
Tee</shirt>

8. XML STRUCTURE
• Entity References
• <message>salary < 1000</message>
• To avoid this error, replace the "<"
character with an entity reference:
• <message>salary &lt; 1000</message
>

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

10. XML STRUCTURE
• Comments in XML
• <!-- This is a comment -->