[graph1_on_file
     [any file,
          may have for url: a URL,
          result of: a writing,
          authoring_date: a time_measure,
          may have for creator: a person,
          may have for Creator: a string,
          may have for size: a computer_memory_unit,
          may have for format: a data_format,
          may have for title: a string,
          may have for Coverage: a thing,
          descr of: a situation]
];