RSS
RSS originated in 1999, and has strived to be a simple, easy to understand format, with relatively modest goals, after it became a popular format, developers wanted to extend it using modules defined in namespaces, with capability, following a simple rule, a RSS feed may contain elements and attributes not described on this page, only if those elements and attributes are defined in a namespace, the elements defined in this document are not themselves members of a namespace, so that RSS can remain compatible with previous versions in the following sense, RSS is by no means a perfect format, but it is very popular and widely supported, having a settled spec is something RSS has needed for a long time and over time to help it become a unchanging thing, to foster growth in the market that is developing around it, and to clear the path for innovation in new syndication formats, therefore, the RSS spec is, for all practical purposes, frozen.
