home / experts / javascript / column103 |
   |
|
|
|
The DTD file contains several types of declarations. First, it includes declarations about the XML document structure. You need to specify each element's content. The root element sales, (see page 2 for a listing of our mydvd XML file), includes the elements summary and data:
<!ELEMENT sales (summary, data)>
Be sure to put all child elements within parentheses and separated by commas. The summary element includes the following elements: heading, subhead, description, author, and date:
<!ELEMENT summary (heading, subhead, description, author, date)>
The data element includes one or more elements of month. You specify repetition with an asterisk:
<!ELEMENT data (month*)>
The month element consists of two elements: name and week (one or more instances):
<!ELEMENT month (name, week*)>
We have reached leaf cells in our XML tree structure. Leaf-cell elements do not include elements but are pure Parsed Character Data (PCDATA). You define their content as (#PCDATA):
<!ELEMENT heading (#PCDATA)> <!ELEMENT subhead (#PCDATA)> <!ELEMENT description (#PCDATA)> <!ELEMENT author (#PCDATA)> <!ELEMENT date (#PCDATA)> <!ELEMENT name (#PCDATA)> <!ELEMENT week (#PCDATA)>
The DTD should also include definitions of the element attributes. The syntax of ATTLIST is quite complicated. In our mydvd XML file, week has two attributes, number and dvds_rented. They are character data (CDATA) and required (#REQUIRED). Here are the definitions of these two attributes:
<!ATTLIST week number CDATA #REQUIRED> <!ATTLIST week dvds_rented CDATA #REQUIRED>
Next: How to define entity references
Legal Notices, Licensing, Permissions, Privacy Policy.
Advertise | Newsletters | Shopping | E-mail Offers | Freelance Jobs 
Produced by Yehuda Shiran and Tomer Shiran
All Rights Reserved. Legal Notices.
Created: February 11, 2002
Revised: February 11, 2002
URL: http://www.webreference.com/js/column103/3.html
