DTD Elements in XML

What are DTD Elements?

• Elements are the building blocks of an XML document.

• In DTD, elements define the structure of the XML by specifying:

  • What elements can appear

  • The order of child elements

  • Whether children are optional or repeatable

  • Whether an element contains text or other elements

Declaring Elements in DTD

<!ELEMENT element-name content-model>

• element-name: The name of the element.

• content-model: Defines what the element contains.

Content Model Types

Occurrence Indicators

Examples

1. Simple Element with Text

<!ELEMENT title (#PCDATA)>

Means <title> contains text only.

2. Element with Sequence of Child Elements

<!ELEMENT book (title, author, year)>

Means <book> must contain <title>, then <author>, then <year>, in that order.

3. Element with Choice

<!ELEMENT status (new | pending | done)>

Means <status> contains one of the three literal values.

4. Element with Mixed Content

<!ELEMENT paragraph (#PCDATA | bold | italic)*><!ELEMENT bold (#PCDATA)><!ELEMENT italic (#PCDATA)>

Means <paragraph> contains text plus zero or more <bold> or <italic> elements.

5. Empty Element

<!ELEMENT br EMPTY>

Means <br> is an empty element with no content.

Summary

If you want, I can help you build a full DTD for your XML document or show how to validate XML using these element declarations!