This document defines and provides examples of XML DTDs. It explains that a DTD defines the structure and elements of an XML document and can be used to validate XML data. It describes the syntax of DTDs and the different types (internal and external). Key points covered include that a DTD specifies elements, attributes, and entities; defines the root element; and element types include PCDATA for parsed character data and CDATA for non-parsed character data. Examples are provided of internal and external DTDs. The document concludes that using a DTD allows different groups to agree on a common standard for exchanging data and applications to validate received and internal data.

1. XML DTD

2. OVERVIEW
1. INTRODUCTIONTO DTD?
2. SYNTAX
3. TYPES
4. EXAMPLES
5. PCDATA
6. CDATA
7. WHY USE A DTD?

3. What is DTD?
■ DTD- in xml DTD define DocumentType Definition.
■ Document structure may be contain elements, attributes, entities.
■ Application can use DTD to verify XML data.
■ It is used to describe the xml language more precisely.

4. STRUCTUREOF DTD
<!DOCTYPE root_element [
<!ELEMENT element_name(element content)>
]>

5. EXAMPLE
<!DOCTYPE employee [
<!ELEMENT employee( empno , name , salary )>
<!ELEMENT empno(#PCDATA)>
<!ELEMENT name(#PCDATA)>
<!ELEMENT salary(#PCDATA)>
]>

6. TYPES
There are two types
1) INTERNAL DTD
2) EXTERNAL DTD

7. An Internal DTD.
INTERNAL DTD
■ Internal elements are declared with the xml file.
■ If the DTD is declared inside the XML file, it must be wrapped inside the
<!DOCTYPE> definition.
SYNTAX
< !DOCTYPE root-element
[ element-declaration] >

8. EXAMPLE
<?xml version=“1.0” encoding=“UTF= 8”>
<! DOCTYPE Address [
<! Element Address(Name, company, Phone)>
<! Element Name (#PCDATA)
<! Element Company (#PCDATA)
<! Element Phone(#PCDATA)
]>
<Address>
<Name>ABC </Name>
<Company>AIT </Company>
<Phone>37973882074</Phone>
</Address>

9. The DTD above is interpreted like this:
■ !DOCTYPE Address defines that the root element of this document is
address
■ !ELEMENT Address defines that the address element must contain
three elements: "Name, company, Phone"
■ !ELEMENT name defines the name element to be of type "#PCDATA"
■ !ELEMENT company defines the company element to be of type
"#PCDATA"
■ !ELEMENT phone defines the phone element to be of type "#PCDATA"

10. An external DTD
EXTERNAL DTD
■ External element are declared outside the xml file.
■ If the DTD is declared in an external file, the <!DOCTYPE> definition must
contain a reference to the DTD file.
SYNTAX
< !DOCTYPE root-element
element system
“file-name”>

11. EXAMPLE
<?xml version=“1.0” encoding=“UTF= 8”>
<!DOCTYPE Address SYSTEM “Address.dtd">
<Address>
<Name>ABC</Name>
<Company>AIT</Company>
<Phone>472397455<Phone>
</Address>

12. The content of the DTD file address.dtd are as shown-
<! Element Address(Name, company, Phone)>
<! Element Name (#PCDATA)>
<! Element Company (#PCDATA)>
<! Element Phone(#PCDATA)>

13. PCDATA
■ PCDATA means parsed character data
■ character data - the text found between the start tag and the end tag of
an XML element.
■ PCDATA is text that will be parsed by a parser
■ Tags inside the text will be treated as markup and entities will be
expanded

14. CDATA
■ CDATA also means character data
■ CDATA is text that will NOT be parsed by a parser
■ Tags inside the text will NOT be treated as markup and entities will not
be expanded.

15. Why use a DTD?
XML provides an application independent way of
sharing data.
With a DTD, independent groups of people can agree to
use a common DTD for interchanging data.
Your application can use a standard DTD to verify that
data that you receive from the outside world is valid.
You can also use a DTD to verify your own data.

16. THANKYOU
created and presented by:
DEEKSHA- 01124802017
HARSHIT MISHRA- 01224802017
HEENA- 01324802017
HIMANSHI SINGH- 0144802017