vBulletin Manual - HTML Doctype

$stylevar[htmldoctype]

The HTML doctype StyleVar controls the first line of the HTML code for every vBulletin page.

It is used to instruct the browser how to render the page, according to a particular type of HTML.

For example, the HTML doctype for XHTML 1.0 Transitional, which is the default for vBulletin 3 is this:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

Another popular doctype is that for HTML 4.0 Transtional. This doctype is less strict than XHTML, but getting consistent layout results with different browsers is more difficult using HTML 4.0 than it is with XHTML 1.0.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

The HTML Doctype is particularly important for visitors using Microsoft Internet Explorer 6, as the inclusion of a doctype declaration at the top of an HTML page switches Internet Explorer into 'Standards Compliant Rendering' mode, causing the browser to be far less tolerant of sloppy or incorrect HTML code, and generally to render pages in a manner more similar to that used by other browsers.

Note:

You may leave the HTML doctype completely blank, but if you do so, Internet Explorer 6 will use the 'Quirky Rendering' mode as used by previous versions of Internet Explorer.

When attempting to achieve a layout that will look the same between Internet Explorer, Mozilla, Opera and all the other browsers out there, 'Quirky Rendering' mode can be extremely unhelpful!