In the media-external item type, the data property is a user-defined property computed by the atg.repository.FilePropertyDescriptor class. If the url property is a relative URL, then data is a java.io.File object, which references the file.

As part of defining a ContentRepositoryItem, the item definition must supply a length and a last modified value. In a media-external item, these values are automatically extracted from the File object returned from data.