The N-SET operation allows the SCU to request that the SCP update selected Attribute values for a specific General Purpose Performed Procedure Step SOP Instance. This operation shall be invoked through the use of the DIMSE N-SET Service used in conjunction with the appropriate General Purpose Performed Procedure Step SOP Instance.
The SCP shall return, via the N-SET response primitive, the N-SET Response Status Code applicable to the associated request. Contingent on the N-SET Response Status, the SCP shall update the Referenced Performed Procedure Step Attributes.
The SCP shall accept N-SET request primitives only if the value of the already existing attribute “General Purpose Performed Procedure Step Status” (0040,4002) is “IN PROGRESS”. If the already existing General Purpose Performed Procedure Step Status attribute has another value, the SCP shall send the failure status code as specified in Section F.184.108.40.206.
The SCP may itself modify any Attributes of the General Purpose Performed Procedure Step SOP Instance only after the “General Purpose Performed Procedure Step Status” (0040,4002) has been set to “COMPLETED” or “DISCONTINUED”, or when error conditions require such a modification.
Note: Under exceptional circumstances, it may be necessary for the SCP to itself set the Performed Procedure Step Status (0040,0252) to COMPLETED or DISCONTINUED, for example if the performing device has failed. When the SCU recovers, subsequent N-SETs may fail.