The Markup tab
of Web Settings contains the entire range of HTML, SMIL, SVG, WML, and GoLive proprietary elements that GoLive can read and write. The information stored in the Markup tab is used by the Source Code Editor's Syntax Checker. HTML-standard elements include all those specified by the HTML 2.0 and 3.2 standard publications, plus HTML 4.0 forms tags. You can add elements to the list and edit existing elements as the current HTML standard evolves. In addition, you can import an XML Document Type Definition (DTD) file and bind it to file extensions and mime types.
HTML pane in the Markup tab of Web Settings