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For more about CSS and layers, see Chapter 12, "CSS Positioning, Dreamweaver Layers, and Page Layout."
By accessing that value, you have just navigated the DOM.
Like everything else about computers, the DOM develops and has versions. Basic form access, such as that shown here, is part of the Level 0 DOM. Dynamic HTML, which accesses other page elements, requires the more developed Level 1 DOM. Only browsers 4.0 and above can understand the Level 1 DOM; therefore, only those browsers can handle DHTML.
The DOM is important to you because all DOMs are not the same. The W3C has set out a standard for how the DOM should function in HTML pages. But browsers follow the standard to different degrees. The Mozilla/Netscape 6 DOM is closest to the standard. The Internet Explorer DOM has some differences. The older Netscape 4 DOM varies quite a bit from the standard. This means that, even if you consider only the two major browsers, you have three different DOMs to deal with.
In general, DHTML authors have a choice of the following:
Pick one browser to design for, and ignore the rest.
Try to be as inclusive as possible by using only features that work everywhere.
Try to be reasonably inclusive, but also use new features by putting two or more sets of code in each page, each directed at a different browser.
You can never be completely shielded , however. Certain items will display differently across browsersand across platforms in different browsers. Certain behaviors will behave differently in different browsersor they won't behave at all, despite Dreamweaver's robust coding. This chapter focuses on how to use Dreamweaver tools for dynamically controlling layers. Be aware as you go through it that not everything you do will work equally well in all browser/platform situations.
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