@whynothugo It is based on the wlr-output protocols, which the COSMIC compositor supports. There are some features we need that aren't currently supported in these protocols, but this is enough to get started with our display settings page.
KDL is a human-friendly alternative to XML. It's as easy on the eyes to read as it is to edit by hand. Has some useful tricks for reducing repetitiveness and annotating data types. The spec reached 1.0.0 sometime around 2021, and started with a Rust crate.