Thank you for your interest.
What purpose would the html metadata serve?
The XHTML metadata defines a strict vocabulary that a web page or application can use. For example, early web pages used special tags that were only usable with some browsers.
<FONT> are some examples of tags that modern browsers do not understand. The
xmlns:webapp="http://www.w3.org/2018/webapp" webapp:prefix="z9999999: http://www.w3.org/z9999999/2018/permissions/fileio/" portion defines additional tags that would be reserved for web applications that are not in the current W3C XHTML specification. This would allow the working group to define tags and behaviours that standard web pages do not require.
Why should this require XML compliance?
This is a requirement for controlling the vocabulary and behaviour of the web rendition engine. In addition,
- XML is specifically designed for simple and unambiguous machine interpretation of code.
- XML validity is easy to verify.
- Using strict XHTML reduces the possibility that different web browsers will interpret the markup differently or in an unexpected manner.
How is this api related to accessibility or to the ability of the user to close the page?
W3C describes the goals of Accessibility as follows:
The Web is fundamentally designed to work for all people, whatever their hardware, software, language, location, or ability. When the Web meets this goal, it is accessible to people with a diverse range of hearing, movement, sight, and cognitive ability.
- Historically, many flash based web-applications have not been easy to use for people who have limited sight or the ability to click accurately on a button or menu item.
- Some modern web applications work better. For example, using Google docs, you can hold the ALT key and tap the F key, then hit the DOWN ARROW key to select a file function.
- When the W3C creates a new standard, there is an opportunity to codify accessibility into the new standards in an integrated and thoughtful way.
- Users who have limited motor abilities or are using a platform that does not have a non-modal “Quit Program” command easily available find it difficult to close a malevolent or poorly implemented program running in the browser.