Insert the following two paragraphs at the beginning of the Boundaries section -------------- This resource captures data that may not be in FHIR format. The document can be any object (e.g. file), and is not limited to the formal HL7 definitions of Document . This resource may be a report with unstructured text or report that is not expressed in a DiagnosticReport . This resource may be an  Observation whose value is audio, video or image data. This resource is the preferred representation of such forms of information as it exposes the metadata relevant for interpreting the information. However, in some legacy environments, information may occasionally appear in Observation instead. Systems should be aware of this possibility. This resource is able to contain medical images in a DICOM format. These images may also be made accessible through an  ImagingStudy  resource, which provides a direct reference to the image to a  WADO-RS server . For such images, the WADO-RS framework is a preferred method for representing the images - the WADO-RS service may include rendering the image with annotations and display parameters from an associated DICOM presentation state, for instance. On the other hand, the DocumentReference resource allows for a robust transfer of an image across boundaries where the WADO-RS service is not available. For this reason, medical images can also be represented in a DocumentReference resource, but the DocumentReference.content.attachment.url should provide a reference to a source WADO-RS service for the image.