What does 'A11Y-VER' represent in EPUB metadata?

'A11Y-VER' in EPUB metadata specifically denotes the version number of the EPUB Accessibility specification. This tag is crucial because it indicates the compliance level of the EPUB document with the established accessibility standards, ensuring that the content can be accessed by individuals with disabilities. Knowing the version allows developers and users to understand the capabilities and constraints of the accessibility features available in that particular EPUB file.

This metadata is vital for maintaining consistency and ensuring that users are aware of the specific accessibility guidelines that the document adheres to. By using the correct version number, authors and developers can improve the usability of their publications and ensure they meet legal and best practice standards for accessibility.