This case-sensitive code system http://hl7.org/fhir/imagingselection-status defines the following codes:
Code
Display
Definition
available
Available
The selected resources are available..
entered-in-error
Entered in Error
The imaging selection has been withdrawn following a release. This electronic record should never have existed, though it is possible that real-world decisions were based on it. (If real-world activity has occurred, the status should be "cancelled" rather than "entered-in-error".).
unknown
Unknown
The system does not know which of the status values currently applies for this request. Note: This concept is not to be used for "other" - one of the listed statuses is presumed to apply, it's just not known which one.