10.3.4 N-ACTION Protocol
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### 10.3.4 N-ACTION Protocol

The information necessary for the N-ACTION request and indication DIMSE-N primitives are conveyed in the N-ACTION-RQ Message. The information necessary for the N-ACTION response and confirmation DIMSE-N primitives are conveyed in the N-ACTION-RSP Message.

#### 10.3.4.1 N-ACTION-RQ

The N-ACTION-RQ Message contains fields as defined in Table 10.3-7. Each field shall conform to DICOM encoding and Value Representation as defined in PS3.5. Fields are required as specified in the N-ACTION service definition unless otherwise noted in Table 10.3-7. Fields not specified in the N-ACTION service definition but present in Table 10.3-7 are required by the DIMSE-N protocol.

Table 10.3-7. N-ACTION-RQ Message Fields

Message Field | Tag | VR | VM | Description of Field
--- | --- | --- | --- | ---
Command Group Length | (0000,0000) | UL | 1 | The even number of bytes from the end of the value field to the beginning of the next group.
Requested SOP Class UID | (0000,0003) | UI | 1 | SOP Class UID of the SOP Instance for which the action is to be performed.
Command Field | (0000,0100) | US | 1 | This field distinguishes the DIMSE-N operation conveyed by this Message. The value of this field shall be set to 0130H for the N-ACTION-RQ Message.
Message ID | (0000,0110) | US | 1 | Implementation-specific value that distinguishes this Message from other Messages.
Command Data Set Type | (0000,0800) | US | 1 | This field indicates if a Data Set is present in the Message. This field shall be set to the value of 0101H if no Data Set is present; any other value indicates a Data Set is included in the Message.
Requested SOP Instance UID | (0000,1001) | UI | 1 | Contains the UID of the SOP Instance for which the action is to be performed.
Action Type ID | (0000,1008) | US | 1 | Values for this field are application-specific.
Action Information | (no tag) | - | - | Application-specific Data Set containing additional information related to the operation.

### Note

1. Service Class Specifications contained in PS3.4 define the values needed for the Action Type ID (0000,1008) parameter.

2. Service Class Specifications contained in PS3.4 define the Data Set needed for the Action Information parameter.

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