Yog Script (.ys, .yns) analyzed: its lexer, parser and syntax tree, names resolved, the class index model — what the build and the editors read a source with.
namespace System.Meta;
/// Marks a method as a derive macro: `[Derive(Name)]` on a type runs it on
/// the type (`string Name(Item item)`), and the code it gives is added
/// after the type.
public sealed class DeriveMacro : Attribute {}