I've been posting this question on various weblogs and in private emails. The question is this. Why not add language to the spec that says it's okay for an RSS feed to include elements not defined in the spec, and leave it at that.
Please. God. No.
- Pretty much every element of RSS0.94 is optional, and can be left out. If you also allow arbitrary elements to be added, do you have a specification any more?
- In the RSS 0.9x series, a valid version 0.9x document is also a valid 0.9x+1 document. If you allow arbitrary elements you break this contract, or at least make it impossible to add new elements to the specification. Each added element becomes a redefining of a previously permitted but undefined element.
- It would discourage the adoption of RSS modules (for which there are already a good set of defined standards, and which can be mixed and matched) in favour of a hundred splintered dialects of the core RSS, which may be mutually incompatible.
Oh, and ten points for someone who can tell me where this post's title (Babble out in simile, since the titles are only visible in my RSS feed) comes from, without using Google.
