There's RFC 4151 to keep in mind, TagURI, a scheme for URIs that is independent of URL (but can use it too). One reason to use it would be to mark a page as being the same resource even though the domain or URL had changed.
This is a cool scheme to address the problem of URL-impermanance due to the fact that DNS name ownership/control can change over time. It allows you to specify a URL plus a date.
I wrote a short blog post about the problem a few years back, and the Tag URI scheme ended up being one of the best solutions I came across, which is how I know about it. Some links in that post and comments may be of interest to people: https://masonlee.org/2009/08/21/is-the-web-sticky-enough/
I wrote a short blog post about the problem a few years back, and the Tag URI scheme ended up being one of the best solutions I came across, which is how I know about it. Some links in that post and comments may be of interest to people: https://masonlee.org/2009/08/21/is-the-web-sticky-enough/