ISO-8879 Markup Validator
These forms submit to the validator hosted at HTMLHelp. This package, like the W3C's HTML validation service, uses James Clark's SP validating parser
Differences between W3C Transitional and Tigris Transitional Document Type Definitions
Optional in W3C, required in Tigris
- Height and width attributes are required on img.
- The border, cellspacing, and cellpadding attributes are required on table.
- The body element may contain only block-level elements, as in HTML Strict. This encourages the use of appropriate containers for all text, which in turn aids selection in CSS.
Optional in W3C, disallowed in Tigris
- The br element is not permitted in contexts where block-level elements may occur, to discourage abuse of br as a substitute for structural elements and/or CSS box model properties.
- The background, bgcolor, text, link, vlink, and alink attributes have been removed, as redundant with CSS.
- The align attributes have been removed except on block elements, as redundant with CSS's text-align properties (which apply only to inline content, hence retention of the usage on blocks).
- The center element has been removed, as redundant with div align='center'.
- The valign attribute has been removed, as redundant with CSS's vertical-align property.
- The menu and dir elements have been removed, as redundant with ul, and deprecated.
- The font and basefont elements have been removed, as redundant with CSS's font-family, font-size, and color properties, as well as with the big and small elements.
Disallowed in W3C, permitted in Tigris
- The height attribute has been added to table.
- The wrap attribute has been added to textarea.
- The border attribute has been added to input.
- The marginwidth and marginheight attributes for body have been added because the Netscape 4.x development team elected to implement these proprietary attributes instead of the earlier formulated CSS equivalents.
W3C HTML DOCTYPEs for reference:
- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
- <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"