The [[Questionnaire]], [[ValueSet]] and [[CodeSystem]] resources are retrieved to allow the system to guide the user through the entry process. The [[Binary]] and [[DocumentReference]] resources allow the system to find existing clinical documents that can be within the pre-population process. (Support for retrieval operations on these resources is optional as the relevant CDA or FHIR structures may also be directly generated by the ''Form Filler'' itself.) Finally, the [[QuestionnaireResponse]] resource is used to record the populated form.<br/>Note: Form Fillers that support the 'populate' operation will need to be capable of consuming and rendering a partially completed QuestionnaireResponse in the same manner as if they had retrieved such a QuestionnaireResponse from a ''Form Response Manager''