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;
/// Where the attribute class it marks may stand.
public sealed class AttributeUsage(AttributeTargets on) : Attribute {
/// Where it may stand.
public readonly AttributeTargets ValidOn = on;
public bool AllowMultiple;
public bool Inherited;
}