An application has its own namespace or namespaces and a schema, or a set of schemas, which can be used by applications to generate and/or validate documents in a unique format. The application can uniquely define the format (and properties) of content in a document such that the document is represented in a native format. The document can be stored externally as a markup language file in accordance with the schema of the application. When the format is stored in a markup language, other applications can validate the document stored in accordance with the native format. The other applications can represent the lists in accordance to the degree to which they are aware of the unique properties of the application used to generate the document.