How will HTML 5 manage (decentralized) extensibility?
In its specifications and process, W3C seeks a balance between stability (for interoperability) and flexibility (to accommodate evolution). HTML 5 has a number of extensibility mechanisms, but none yet that satisfies the requirement XML namespaces was designed to address of decentralized extensibility – allowing parties to include their own elements or attributes in content without risk of name collisions (whether those names are the result of a consensus process or not). An HTML Working Group issue on decentralized extensibility is still open and unresolved. The text/html serialization of HTML5 contains extensibility points but does not provide a decentralized mechanism. One of the open questions is what extensibility mechanism can be used such that, when it is parsed from either the HTML or XML serialization, the DOM that results is the same (see HTML Design Principles section 3.5). W3C plans to organize a panel at TPAC 2009 on the topic of decentralized extensibility in HTML and wil
