The Accessible Platform Architectures (APA) working group hopes to designate adapt- as a reserved prefix in HTML 5. You can read the draft proposal on the public-adapt mailing list.
The “Adapt” family of specifications will allow pages to expose generic meanings behind elements, and allow users to “switch” these to versions they understand. A sarcastic sentence could have a literal alternative; words can be swapped with symbols. Like RDFa and Microdata, this will also allow authors to describe meanings behind page elements; unlike prior art, these meanings will be intended for humans and have close synergy with the surrounding markup.
Personalization semantics make pages easier for users to understand, especially neurodivergent users. I like to think of it as primarily—but not exclusively—adding semantic meaning to the page rather than extract data from it.
Enshrining this prefix in HTML could be a huge boon for cognitive accessibility and customization on the Web by hopefully guaranteeing much greater adoption.