A 'simplified' bibliography reference format like bibtex or biblatex.

Uses yaml under the hood and is super simple to understand:

Doan2020:
    type: Article
    title: Kinetics and luminescence of the excitations of a nonequilibrium polariton condensate
    author: ["Doan, T. D.", "Tran Thoai, D. B.", "Haug, Hartmut"]
    doi: "10.1103/PhysRevB.102.165126"
    page-range: 165126-165139
    date: 2020-10-14
    parent:
        type: Periodical
        title: Physical Review B
        volume: 102
        issue: 16
        publisher: American Physical Society

One interesting fact is that it uses one (or multiple) 'parent' keys to signify where something is from which in turn use the same simple keys (type, title, ...) as the original document to describe themselves.
So, instead of a million individual keys to describe an entry we use a more recursive format with each having the same couple keys.
This could be really interesting for a closer papis integration with its standard yaml format for example.

Format readme here.

I am not sure how 'mature' the format is, however.
It has been created for the typst typesetting language afaik, and that is still pretty new/fluctuating as of now as well.