W3c is the human body that tries to standardize this stuff, they produce The foundations, then programmers create their rendering engine to interpret These procedures. It's not at all similar to "all td, th and caption things which happen to be contained by a div element with a category of https://natural-bookmark.com/story19337350/prestashop-popup-on-exit-page-on-browser-tab-close-event-things-to-know-before-you-buy