How to add HTML <form> rel opener Attribute

opener will appear that robots won't open the page.

index.html

Example: HTML

<!DOCTYPE html>
<html>
<body>
<h2 style="color: green">Horje</h2>
<h2>HTML form Attribute</h2>
<form rel="opener" action="mypage.php">
<input type="search" placeholder="search here" />
<input type="button" value="search" />
</form>
</body>
</html>

Output should be:

Type:	html
Category:	Web Tutorial
Sub Category:	HTML Tag
Uploaded by:	Admin