Describe what a document is allowed to contain.

AEON keeps structure and validation separate. A document can stay readable and expressive, while AEOS defines what paths, value kinds, reference forms, and attribute payloads are acceptable.

That makes validation visible rather than hidden inside application code.

The schema states required paths and the kinds of values they accept. A validator checks AES against that contract without changing the document itself.

aeos:schema = {
  id = "com.example.release"
  version = "1"
  rules = {
    $.document.title = {
      required = true
      type = "StringLiteral"
    }
    $.document.published = {
      type = "BooleanLiteral"
    }
    $.document.tags = {
      type_is = "list"
    }
    $.document.measurements[0] = {
      type = "NumberLiteral"
      attributes = {
        unit = {
          required = true
          type = "StringLiteral"
        }
      }
      closed_attributes = true
    }
  }
}

The document remains ordinary AEON. Validation is a later step that confirms whether the document satisfies the contract you chose to apply.

document:object = {
  title:string = "Release notes"
  published:boolean = true
  tags:list = ["spec", "draft"]
  measurements:list = [@{unit:string = "cm"}:number = 3]
}

Because the schema is visible, validation failures can be explained in terms of the document itself: wrong value kind, missing path, unexpected binding, or missing attribute metadata. That is easier to reason about than hidden runtime assumptions.

document:object = {
  title:string = "Release notes"
  published:string = "yes"
  tags:list = ["spec", 42]
  measurements:list = [@{precision:number = 2}:number = 3]
}