XML Syntax Rules

XML Syntax Rules

XML (Extensible Markup Language) follows strict syntax rules to ensure well-formed documents.

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1. XML Must Have a Root Element

Every XML document must have a single root element that contains all other elements.

<library>
    <book>
        <title>XML Basics</title>
        <author>John Doe</author>
    </book>
</library>

• <library> is the root element.
• All other elements are nested inside it.

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2. XML Tags Must Be Properly Closed

XML elements must have opening and closing tags. ✅ Correct:

<title>XML Guide</title>

❌ Incorrect:

<title>XML Guide  <!-- Missing closing tag -->

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3. XML Tags Are Case-Sensitive

✅ Correct:

<Title>XML Guide</Title>

❌ Incorrect:

<Title>XML Guide</title>  <!-- Case mismatch -->

• <Title> and <title> are different elements.

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4. XML Elements Must Be Properly Nested

✅ Correct:

<book>
    <title>XML Basics</title>
    <author>John Doe</author>
</book>

❌ Incorrect:

<book>
    <title>XML Basics
    <author>John Doe</title>  <!-- Incorrect nesting -->
</author>
</book>

• The <author> tag must be inside <book> but outside <title>.

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5. XML Attribute Values Must Be Quoted

✅ Correct:

<book title="XML Basics" author="John Doe"/>

❌ Incorrect:

<book title=XML Basics author=John Doe/>  <!-- Missing quotes -->

• Attribute values must be enclosed in quotes ("" or '').

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6. XML Allows Self-Closing Tags

If an element has no content, you can use a self-closing tag:

<book title="XML Basics"/>

This is equivalent to:

<book title="XML Basics"></book>

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7. XML Supports Comments

Comments in XML are written like this:

<!-- This is a comment -->
<book>
    <title>XML Basics</title>
</book>

❌ Incorrect:

<!-- This is a comment --!>  <!-- Wrong syntax -->

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8. XML Does Not Allow Special Characters Without Escaping

Some characters have special meanings and must be escaped: | Character | Escape Code |

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