In HTML, you can code a Boolean attribute as

the attribute name, an equals sign, and 1 or 0

the attribute name, an equals sign, and on or off

just the attribute name

the attribute name, an equals sign, and yes or no

When you use a Markup Validation Service to validate the HTML for one web page,

a trivial coding error can cause multiple validation errors

you can be sure that the validated page will work correctly in all browsers

the page won\'t run in a browser if it isn\'t valid you need to validate all pages of your site