MACROMEDIA DREAMWEAVER 8-EXTENDING DREAMWEAVER Bedienungsanleitung PDF herunterladen (Seite 20)

categories include Dynamic Pages (that use languages such as ASP, ColdFusion, and PHP)

and Page Designs (that you can use as a starting point when creating your own site). You

can access speciﬁc page types by choosing from the list of categories in the left column of

the dialog box that includes Dynamic, Templates, CSS Style Sheets, Framesets, and Page

Designs. You won’t use any of these additional page types in this exercise, but you should be

aware of them. The contents of the middle column of the dialog box change depending

upon the category selected in the left column.

Understanding XHTML, XML and

Document Type Definitions

Behind the visual appearance of a Web page is code, called a markup language, that is

used to produce what a visitor sees in their browser

—

the markup describes the struc-

ture and appearance of a page by labeling elements such as text and images with

instructions, in the form of tags and their attributes, as to how those elements should be

displayed. Hypertext Markup Language (HTML) is currently one of the most well-

known markup languages; however, HTML is limited in nature, particularly in that new

features are generally not backward-compatible, and there are a wide number of com-

patibility issues with HTML for cross-browser use. HTML is an older markup language

that is being phased out of use because it doesn’t meet current Web standards, nor

does it have the potential to evolve to match those standards.

Extensible Hypertext Markup Language (XHTML) replaces and extends the capabilities of

HTML by reforming HTML as an Extensible Markup Language (XML) language. XML

markup emphasizes and facilitates the separation of structure, content, and presentation by

specifying the content and structure of a page, but not the appearance or presentation

—

the definition of all presentation is handled separately through other means, such as CSS.

The advantages of using XHTML include both backward- and forward-compatibility,

operability on alternate Web access devices such as cell phones or handheld comput-

ers, and the potential for extensibility. XHTML 1.0 Transitional is a version of XHTML

that allows the use of some HTML elements that are deprecated

—

marked as obsolete

by the World Wide Web Consortium (W3C), which develops Web standards to ensure

compatibility throughout the industry

—

and therefore not available in stricter versions of

XHTML. Because allowing these deprecated elements enables backward-compatibility

through the conversion from HTML to XHTML, XHTML 1.0 Transitional is currently the

recommended markup language for Web development.

The use of these languages is defined through the Document Type Definition (DTD).

Although invisible to the visitor, the DTD is located at the beginning of the code that com-

prises the Web page. The DTD declares the syntax of the markup language for the page

—

that is, it defines how the browser or other Web access device should interpret the page.

20 LESSON 1

01_DW8 tfs(1-38).qxd 03/06/2006 12:20 PM Page 20

ISBN: 0-558-13856-X

Published by Peachpit Press, a Pearson Company.

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