The SCU uses the N-GET Service Element to request the SCP to get a Modality Performed Procedure Step Retrieve SOP Instance. The SCU shall specify in the N-GET request primitive the UID of the SOP Instance to be retrieved, which is a UID of a Modality Performed Procedure Step SOP Instance. The SCU shall be permitted to request that Attribute Values be returned for any Modality Performed Procedure Step Retrieve SOP Class Attribute specified in Table F.8.2-1. Additionally values may be requested for optional Modality Performed Procedure Step IOD Attributes.
The SCU shall specify the list of Modality Performed Procedure Step Retrieve SOP Class Attributes for which values are to be returned. The encoding rules for Modality Performed Procedure Step Attributes are specified in the N-GET request primitive specification in PS 3.7.
In an N-GET operation, the values of Attributes which are defined within a Sequence of Items shall not be requested by an SCU.
The SCU shall be capable of receiving all requested Attribute Values provided by the SCP in response to the N-GET indication primitive. The SCU may request Attribute Values for optional Attributes which 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.