The SCU shall specify in the Requested SOP Instance UID parameter of the N-ACTION request primitive the UID of the General Purpose Scheduled Procedure Step SOP Instance for which it wants to modify Action Information, as specified in Table F.10.2-1.
Note: In the usage described here, there is no explicit creation of a SOP Instance upon which an N-ACTION primitive may operate. Instead, the N-ACTION primitive operates upon a SOP Instance previously created by the SCP. The SCU will retrieve the value for the SOP Instance UID by means of the General Purpose Worklist C-FIND service.
The SCU shall specify the requested value for the Attribute “General Purpose Scheduled Procedure Step Status” (0040,4001) in the Action Information.
The encoding rules for General Purpose Scheduled Procedure Step Action Information are specified in the N-ACTION request primitive specification in PS 3.7
The SCU shall not send N-ACTION request primitives for a General Purpose Scheduled Procedure Step SOP Instance when the Attribute “General Purpose Scheduled Procedure Step Status” (0040,4001) of that SOP Instance is “COMPLETED” or “DISCONTINUED”.
The SCU shall supply a “Transaction UID” Attribute (0008,1195) to identify the Modify GP-SPS Information Request that requests a modification of the value of the Attribute “General Purpose Scheduled Procedure Step Status” (0040,4001) to “IN PROGRESS”. The same Transaction UID shall be used to request a modification of the status from “IN PROGRESS” to: “SUSPENDED”, “SCHEDULED”, “COMPLETED” or “DISCONTINUED”. Once the status has any other value than “IN PROGRESS” this Transaction UID shall no longer be used.
Note: This “Transaction UID” Attribute (0008,1195) is used to identify the single transition into the “IN PROGRESS” state, not the ownership of the General Purpose Procedure Step SOP Instance.