Table C.4.23-1 specifies the Attributes used to describe which Instances are available and their relationships.
INSTANCE AVAILABILITY NOTIFICATION MODULE ATTRIBUTES
|Attribute Name||Tag||Attribute Description|
|Referenced Performed Procedure Step Sequence||(0008,1111)||Uniquely identifies the Performed Procedure Step SOP Instance to which this availability notification instance is related, if any. Zero or one Item shall be included in this sequence. Notes: 1. This may refer to a different PPS than that encoded in the composite instances themselves. 2. It is typically used for notification about instances created as a consequence of some scheduled activity.|
|>Include SOP Instance Reference Macro Table 10-11|
|>Performed Workitem Code Sequence||(0040,4019)||A sequence that conveys the (single) type of procedure performed. Only a single Item shall be included in this sequence.|
|>>Include Code Sequence Macro Table 8.8-1||Baseline CID 9231.|
|Study Instance UID||(0020,000D)||Unique identifier for the Study of which all the Instances referenced in this notification are part.|
|Referenced Series Sequence||(0008,1115)||Sequence of Items where each Item includes references to Instances within the same Series. One or more Items shall be included in this Sequence.|
|>Series Instance UID||(0020,000E)||Unique identifier of the Series of which all the Instances referenced in this Item are part.|
|>Referenced SOP Sequence||(0008,1199)||Sequence of Items where each Item includes a reference to a single Instance within this Series. One or more Items shall be included in this Sequence.|
|>>Include SOP Instance Reference Macro Table 10-11|
|>>Instance Availability||(0008,0056)||The availability of the referenced Instance. See Section C.22.214.171.124|
|>>Retrieve AE Title||(0008,0054)||Title of the DICOM Application Entity from which the referenced Instance may or may not be retrievable, i.e. the scope for which Instance Availability (0008,0056) applies. See Section C.126.96.36.199.|
|>>Retrieve Location UID||(0040,E011)||Unique identifier of the system where the Composite Object(s) may be retrieved on the network.|
|>>Retrieve URI||(0040,E010)||Retrieval access path to the referenced SOP instance(s). Includes fully specified scheme, authority, path, and query in accordance with RFC 2396.|
|>>Storage Media File-Set ID||(0088,0130)||The user or implementation specific human readable identifier that identifies the offline storage media on which the instance resides.|
|>>Storage Media File-Set UID||(0088,0140)||Uniquely identifies the offline storage media on which the instance resides.|
The Enumerated Values for Instance Availability (0008,0056) are:
“ONLINE” means the instances are immediately available from the Retrieve AE Title (0008,0054), and if a C-MOVE were to be requested, it would succeed in a reasonably short time
“NEARLINE” means the instances need to be retrieved from relatively slow media such as optical disk or tape, and if a C-MOVE were to be requested from the Retrieve AE Title (0008,0054), it would succeed, but may take a considerable time
“OFFLINE” means that a manual intervention is needed before the instances may be retrieved, and if a C-MOVE were to be requested from the Retrieve AE Title (0008,0054), it would fail (e.g., by timeout) without such manual intervention.
“UNAVAILABLE” means the instances cannot be retrieved from the Retrieve AE Title (0008,0054), and if a C-MOVE were to be requested, it would fail. Note that SOP Instances that are unavailable from this AE may be available from other AEs, or may have an alternate representation that is available from this AE.