HTML Reference Guide
<LISTING> ... </LISTING> LISTING
The Listing element displays all characters "As-Is" in the browser as a fixed-width font. Recommended display of this element is a 132 character line length. Until a closing LISTING tag is encountered, other HTML elements are displayed on screen as text and not evaluated.
The rules for this sort of behavior can have many consequences in parsing techniques, thus the use of this element is strongly discouraged (the Pre element should be used instead.) This element (as well as the XMP element) is no longer standard HTML. They are considered "obsolete" in HTML specifications beginning with 2.0, but they should be implemented by browsers for backward compatibility.