The Comprehensive HTML Cross Reference


HTML Standards and Support

Not all Web browsers support all HTML tags. The World Wide Web Consortium develops and maintains standards for HTML and related technologies. Major vendors, including Netscape and Microsoft, have also developed a number of extensions to the HTML standards. In this web site, we have attempted to rigorously categorise each HTML tag and each of its attributes (if applicable) according to which standards it conforms to, and according to which browsers support it. This page is a key to the graphical indicators we use throughout the site to indicate support for the various tags and their attributes.

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Support for tags

Throughout this site we use the following graphical table at the beginning of a tag description to indicate support for the tag. If the table is missing, it means that the tag is defined in the HTML 2.0 standard and is supported by all graphical browsers including Netscape, Microsoft Explorer, and Mosaic.

Support:  HTML:2.0, 3.0, 3.2  Netscape:1.1+  MS Explorer:2.0+
Within the table, you can click on Support to get back to this page. The icons are used as follows:

 HTML: indicates standards defined by the World Wide Web Consortium.

 Netscape: indicates support in Netscape's Navigator web browser.

 MS Explorer: indicates support in Microsoft's Internet Explorer web browser.

The numbers after each icon indicate the versions (of the standards or of the browsers) that support the tag. A plus sign ( + ) after a number means that version and all versions above. The example above would indicate a tag that is defined in HTML standards 2.0, 3.0, and 3.2; that is supported by Netscape Navigator versions 1.1 and above; and that is supported by Microsoft Internet Explorer versions 2.0 and above.

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Support for attributes

Some tags have attributes, and sometimes a browser will support a tag but will not support all the attributes. When these exceptions arise, we use the following icons on the specific attributes in question:

(HTML 3.0 Only) identifies attributes in the now-defunct HTML 3.0 specification that are not part of any official specification.. Many of these were supported by browsers like Netscape Navigator and Microsoft Explorer.

(HTML 3.2 Only) identifies attributes in the May 1996 HTML 3.2 specification. These are almost all supported by Netscape Navigator 2.0 or higher and Microsoft Explorer 2.0 or higher.

(Netscape Extension) identifies attributes supported by Netscape Navigator 2.0 that are not in any official HTML specification. Some attributes identified with this icon were also supported by earlier versions.

(Microsoft Extension)identifies attributes supported by Microsoft Explorer 2.0 that are not in any official HTML specification. Some attributes identified with this icon were also supported by version 1.0.

(Microsoft Extension 3.0) identifies attributes supported by Microsoft Explorer 3.0 that are not in any official HTML specification.

Browsers are supposed to ignore tags and attributes they do not know. Some, however, do not. For example some versions of Mosaic do not display the text and images inside a <TABLE> tag at all, though if they ignored <TABLE>, <TR>, and <TD> the text inside should come through. Use caution when using a tag that is not supported by all browsers.

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In addition to our main indexes (the compact index and the complete index), there are four other indexes that list the tags according to the standards and browsers that support them.

The Comprehensive HTML Cross Reference was created as a service to the Internet community. It represents a joint effort of Scott Williams of CDI Corporate Education Services and Kate Gregory of Gregory Consulting and is fully protected by Copyright © 1995 - 2001. Please report any errors or omissions to Kate Gregory.