Property List

A block-level definition-list: an ordered sequence of (key, value) rows where each value can mix inline content (text, ResourceLinks) and nested blocks (recursive PropertyLists for embedded resources, future Tables). HTML backends emit `<dl>` with `<dt>` / `<dd>`. Markdown backends emit bolded key with indented value. The natural rendering for "this resource has these properties" — what the universal renderer produces for any resource by walking its statements.