HTML Reference Guide
<PLAINTEXT> ... PLAINTEXT
The original specification for this obsolete element states that it be used to stop the parsing of HTML tags by the browser. What follows after is not SGML. The PLAINTEXT element specification did not accept a closing tag. The text after the opening PLAINTEXT tag is typically rendered as a fixed-width font.
This element is no longer standard HTML. It is considered "obsolete" in the HTML 2.0 , 3.0 and 3.2 specifications, and is not mentioned in the HTML 4.0 draft. It may be implemented by browsers for backward compatibility.
this is text that is not evaluated by the browser