DICOM PS3.4 2017b - Service Class Specifications

CC.2.7.2 Service Class User Behavior
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#### CC.2.7.2 Service Class User Behavior

The SCU uses the N-GET to request the SCP to provide Attributes and values of a Unified Procedure Step Instance. Since all UPSs are created as instances of the UPS Push SOP Class, the Affected SOP Class UID (0000,0002) in the N-GET request shall be the UID of the UPS Push SOP Class. See Section CC.3.1 for further details.

The SCU shall specify in the N-GET Service Element the UID of the SOP Instance from which Attributes are to be retrieved.

The SCU shall specify the list of Unified Procedure Step Attributes for which values are to be returned. The SCU shall not specify Attributes that are defined within a Sequence, but rather specify the sequence itself to be retrieved in its entirety.

The SCU shall not request the value of the Transaction UID (0008,1195) Attribute.

The SCU may request Attribute Values for optional Attributes that are not maintained by the SCP. In such a case, the SCU shall function properly regardless of whether the SCP returns values for those Attributes or not. This Service Class Specification places no requirements on what the SCU shall do as a result of receiving this information.

### Note

In order to accurately interpret the character set used for the Attribute Values returned, it is recommended that the Attribute Value for the Specific Character Set (0008,0005) be requested in the N-GET request primitive.

The SCU shall be permitted to request and shall be capable of receiving values for any Attribute as specified in Table CC.2.5-3. Additionally, values may be requested for optional Attributes.

The SCU shall be capable of receiving all requested Attribute Values provided by the SCP in response to the N-GET indication primitive.

### Note

If the SCU or the user will need access to the final state Attributes it is the responsibility of the SCU to Subscribe (see Section CC.2.2) in order to receive State Change Events and then N-GET the necessary Attributes promptly upon notification of a state change to COMPLETED or CANCELED. If the SCU sets the Deletion Lock when subscribing, a COMPLETED or CANCELED instance will continue to persist on the SCP, using resources. It is important that the SCU remove the lock (e.g., by unsubscribing) after doing the N-GET on the COMPLETED or CANCELED instance.

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DICOM PS3.4 2017b - Service Class Specifications