How to add HTML <button> formenctype text/plain Attribute

<!DOCTYPE html> <html> <body> <h1>The button formenctype attribute</h1> <form action="/action_page_binary.asp" method="post"> <label for="fname">First name:</label> <input type="text" id="fname" name="fname" value="Ståle"><br><br> <button type="submit">Submit with character encoding</button> <button type="submit" formenctype="text/plain">Submit without character encoding</button> </form> </body> </html>