Instructor: Jennifer Kyrnin
The XML class from About.com is a free, 10-week class about the eXtensible Markup Language or XML. The lessons are sent weekly by email, but the class is self-paced. You may read and review any of the lessons at any time. You can also have them resent to you. The following articles are part of week 6.
When you write HTML with some editors, you'll notice that there is this strange line written across the top:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
While you may not know what it is, it still serves a purpose, and with XML that line of code is required to write a well-formed document.
A DTD is the grammar of an XML page. It is an acronym that stands for Document Type Definition. It contains the elements, attributes, entities, and notations used in the XML document.
Elements, entities, attributes and notations are the building blocks of a DTD. Once you understand what each of these are, you can easily write your own DTD and be on your way to writing XML applications.
This is a self-paced class. This means that if you need more time than a week to review the lessons, that is fine. And if you finish the lessons before the next week, you can request the next lesson.