This document addresses the newer Netscape extensions and attributes, offers HTML 3.0 alternatives, and gives guidelines on their use.
Netscape corporation has extended HTML with new Netscape extensions and attributes. Since some of the tags are not currently in the HTML 3.0 draft people often ask, which Netscape extensions should I use? This question should be rephrased as what HTML 3.0 does Netscape support?
Since Netscape corporation has pledged to support HTML 3.0 and most of the Netscape extensions have HTML 3.0 equivalents, you should go with HTML 3.0 as it will work on all browsers.
Mike Meyer has written Use of Netscape tags in HTML which points out which Netscape tags and attributes to use and which to avoid (font, basefont, blink, width <HR>, and type <OL> for example). He covers Netscape 1.0 but does not cover the newer versions of Netscape (currently 1.1N). There are some patterns here, HTML was meant to be extended by the use of attributes, so Netscape's new attributes generally will be in HTML 3.0, but Netscape's new tags generally won't (center, font, basefont).
Careful reading of the HTML 3.0 draft revealed that the background attribute of the <BODY> tag is indeed included in the latest draft. The Netscape BGCOLOR attribute is not, however, and should not be used.
The BACKGROUND attribute tiles the background with the referenced graphic, with the subsequent HTML overlaying this graphic. BACKGROUND graphics slow down the display of your page the first time it's displayed, subsequent entries into this page or similarly tiled pages will benefit from the cache. BACKGROUND graphics should be used sparingly, on less-heavily accessed pages. Smaller graphics will display the page faster. The graphic should also be light, darker backgrounds make reading the default text difficult. Now, where was that Netscape Hall of Shame...
By popular demand HTML 3.0 has added Tables and Netscape expanded the draft with their tables. Note that Netscape's way of specifying column width is different from the HTML 3.0 way. Netscape uses the width attribute in the TD and TH tags, whereas HTML 3.0 suggests a colspec attribute in the table tag. Mosaic now supports tables also so they may be used more freely.
Tables are a very powerful new feature that open up many possibilities. Since Netscape is currently the only popular browser to support tables, they should be used sparingly (with an alternative for other browsers) or only in situations where the use of Netscape is assured (i.e., in a kiosk).
The Netscape <CENTER> tag should be replaced with the CENTER attribute. The CENTER tag is NOT in the HTML 3.0 draft, the CENTER attribute is. Use <P ALIGN=CENTER> and <H2 ALIGN=CENTER> instead of CENTER. The CENTER attribute will work on Netscape and Mosaic. In the future the <DIV> (DIVision) tag can be used to center sections of text and graphics.
The <IMG> tag is used to incorporate in-line graphics (typically icons or small graphics) into an HTML document. The ALIGN attribute is now included in the latest HTML 3.0 draft, and allows text to flow around graphics. I suspect the ALIGN attribute was added due to Netscape's influence, and it should be used sparingly. The new FIG (FIGure) tag is more powerful, and should be used instead once browsers support it. It provides captions, overlays, and client-side ISMAPs.
The <HR> tag is used for horizontal rules that act as dividers between sections. Netscape's SIZE attribute is NOT in the current HTML 3.0 draft, and should not be used. The HTML 3 HR provides a graphic option for more flexibility (SRC). The SRC attribute can be used to designate a custom graphic. The WIDTH attribute is also not included in the HTML 3.0 draft.
Here's an hyperized excerpt from the HTML 3.0 draft overview that gives an overview of HTML 3's new features:
HTML 3.0 builds upon HTML 2.0 and provides full backwards compatibility. Tables have been one of the most requested features, with text flow around figures and math as runners up. Traditional SGML table models, e.g. the CALS table model, are really complex. The HTML 3.0 proposal for tables uses a lightweight style of markup suitable for rendering on a very wide range of output devices, including braille and speech synthesizers.
HTML 3.0 introduces a new element: FIG for inline figures. This provides for client-side handling of hotzones while cleanly catering for non-graphical browsers. Text can be flowed around figures and you can control when to break the flow to begin a new element.
Including support for equations and formulae in HTML 3.0 adds relatively little complexity to a browser. The proposed format is strongly influenced by TeX. Like tables, the format uses a lightweight style of markup - simple enough to type in by hand, although it will in most cases be easier to use a filter from a word processing format or a direct HTML 3.0 wysiwyg editor. The level of support is compatible with most word processing software, and avoids the drawbacks from having to convert math to inline images.
The Web has acted as a huge exercise in user testing, and we have been able to glean lots of information from the ways people abuse HTML in trying to get a particular effect; as well as from explicit demand for new features. HTML 3.0, as a result, includes support for customised lists; fine positioning control with entities like &emspace; horizontal tabs and horizontal alignment of headers and paragraph text.
Additional features include a static banner area for corporate logos, disclaimers and customized navigation/search controls. The LINK element can be used to provide standard toolbar/menu items for navigation, such as previous and next buttons. The NOTE element is used for admonishments such as notes, cautions or warnings, and also used for footnotes.
Forms have been extended to support graphical selection menus with client-side handling of events similar to FIG. Other new form field types include range controls, scribble on image, file upload and audio input fields. Client-side scripting of forms is envisaged with the script attribute of the FORM element. Forms and tables make for a powerful combination offering rich opportunities for laying out custom interfaces to remote information systems.
To counter the temptation to add yet more presentation features, HTML 3.0 is designed (but doesn't require) to be used together with style sheets (work on style sheets) which give rich control over document rendering, and can take into account the user's preferences, the window size and other resource limitations, such as which fonts are actually available. This work will eventually lead to smart layout under the author's control, with rich magazine style layouts for full screen viewing, switching to simpler layouts when the window is shrunk.
Last modified on May 4, 1995 by aking@ic.net If you find any errors or want to contribute please e-mail me.