Sunday 18th of March 2018 02:57:57 AM

by Eric A. Meyer
ISBN 1-56592-622-6
First edition, published May 2000.
(See the catalog page for this book.)

Search the text of Cascading Style Sheets: The Definitive Guide.

You can also leave out some values and have their defaults kick in, like this:

H3 {color: gray; border-bottom: 3px solid;}

Since no border color is declared, the default value (the element's foreground) is applied instead, as we can see in Figure 7-48. Just remember that if you leave out a border style, the default value of none will prevent your border from appearing at all.

Table of Contents

Copyright Page
Chapter 1: HTML and CSS
Chapter 2: Selectors and Structure
Chapter 3: Units and Values
Chapter 4: Text Properties
Chapter 5: Fonts
Chapter 6: Colors and Backgrounds
Chapter 7: Boxes and Borders
Chapter 8: Visual Formatting
Chapter 9: Positioning
Chapter 10: CSS2: A Look Ahead
Chapter 11: CSS in Action
Appendix A: CSS Resources
Appendix B: HTML 2.0 Style Sheet
Appendix C: CSS1 Properties
Appendix D: CSS Support Chart
Library Navigation Links

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XML is structured

When you create your data using an XML editor (that you can write), you can not only input the content of your data, but also define the structural relationships that exist inside your data. By allowing you to define your own tags and create the proper structural relationships in your information (with a DTD), you can use any XML parser to check the validity and integrity of the data stored in your XML documents. This makes it very easy to validate the structure and content of your information when you use XML. Without XML, you could also provide this validation feature at the expense of developing the code to this yourself. XML is a great time saver because most of the features that are available in XML are used by most programmers when working on most projects.

By using XML and Java, you can quickly create and use information that is properly structured and valid. By using (or creating) DTDs and storing your information in XML documents, you have a cross-platform and language independent data validation mechanism (for free) in all your projects!

You might use XML to define file formats to store information that is generated and used by your applications. This is another use of the structured nature of XML. The only limitation is that binary information can't be embedded in the body of XML documents. For example, if you wrote a word processor in Java, you might choose to save your word processor documents to an XML (actually your ApplicationML) file. If you use a DTD then your word processor would also get input file format validation as a feature for free. There are many other advantages to using XML and a file storage format for your applications which will be illustrated later in the chapter.

XML documents are easily committed to a persistence layer

XML documents may be stored in files or databases. When stored in files, XML documents are simply plain text files with tags (and possibly DTDs). It is very easy to save your XML documents to a text file and pass the text file around to other machines, platforms and programs (as long as they can understand the data). In the worst case scenario, XML documents (files) can be viewed in a text editor on just about any platform.

XML documents are also naturally committed to a database (relational or object) or any other kind of XML document store. There are commercial products available which allow you to save XML documents to an XML storage layer (which is not a database per se), like Datachannel's XStore and ODI's eXcelon. These XML store solutions are quite expensive ($10,000 to $20,000 range).

XML documents are also quite naturally retrieved from a persistence layer (databases, file systems, XML stores). This lends XML to be used in real world applications where the information being used by different parts of a system is the most important thing.

XML is platform independent, textual information