Y.5 Association Negotiation
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## Y.5 Association Negotiation

Association establishment is the first phase of any instance of communication between peer DICOM AEs. AEs supporting DICOM Query/Retrieve SOP Classes utilize Association establishment negotiation by defining the use of Application Association Information. See PS3.7 for an overview of Association negotiation.

SOP Classes of the Composite Instance Root Retrieve Service, which include retrieval services based on the C-MOVE and C-GET operations, use the SCP/SCU Role Selection Sub-Item to identify the SOP Classes that may be used for retrieval.

### Y.5.1 Association Negotiation for C-MOVE and C-GET SOP Classes

Rules are as specified in Section C.5.3, except that the extended negotiation sub-item, if used, shall be used as defined in Section Y.5.1.1.

### Note

1. Though converted images may be specified by their SOP Instance UID in the Request Identifier, which is always at or below the instance level, there remains a need for extended negotiation and specification of the Query/Retrieve View in order to assure that referential integrity is maintained within the returned SOP Instances (e.g., that a reference to a SOP Instance UID is to a converted image or not, as appropriate).

2. Relational-retrieval is not applicable to these SOP Classes, hence the Extended Negotiation Sub-Item does not include the use of that byte.

#### Y.5.1.1 SOP Class Extended Negotiation

The SOP Class Extended Negotiation allows, at Association establishment, peer DICOM AEs to exchange application Association information defined by specific SOP Classes. This is achieved by defining the Service-class-application-information field. The Service-class-application-information field is used to define support for Enhanced Multi-Frame Image Conversion.

This negotiation is optional. If absent, the default condition shall be:

- no Enhanced Multi-Frame Image Conversion support

The Association-requester, for each SOP Class, may use one SOP Class Extended Negotiation Sub-Item. The SOP Class is identified by the corresponding Abstract Syntax Name (as defined by PS3.7) followed by the Service-class-application-information field. This field defines:

- Enhanced Multi-Frame Image Conversion support by the Association-requester

The Association-acceptor, for each SOP Class Extended Negotiation Sub-Item offered, either accepts the Association-requester proposal by returning the same value (1) or turns down the proposal by returning the value (0).

If the SOP Class Extended Negotiation Sub-Item is not returned by the Association-acceptor then Enhanced Multi-Frame Image Conversion is not supported (default condition).

If the SOP Class Extended Negotiation Sub-Items do not exist in the A-ASSOCIATE indication they shall be omitted in the A-ASSOCIATE response.

##### Y.5.1.1.1 SOP Class Extended Negotiation Sub-Item Structure (A-ASSOCIATE-RQ)

The SOP Class Extended Negotiation Sub-Item consists of a sequence of mandatory fields as defined by PS3.7. Table Y.5.1-1 defines the Service-class-application-information field for the C-MOVE and C-GET operations.

Table Y.5.1-1. SOP Class Extended Negotiation Sub-Item (Service-Class-Application-Information Field) - A-ASSOCIATE-RQ

Item Bytes | Field Name | Description of Field
--- | --- | ---
1 | Unused | Reserved - shall be 0
2 | Enhanced Multi-Frame Image Conversion | This byte field defines whether or not the Attribute Query/Retrieve View (0008,0053) shall be used to adjust the view returned in queries to consider conversion to or from Enhanced Multi-Frame Images. It shall be encoded as an unsigned binary integer and shall use one of the following values 0 - Query/Retrieve View not supported 1 - Query/Retrieve View supported

##### Y.5.1.1.2 SOP Class Extended Negotiation Sub-Item Structure (A-ASSOCIATE-AC)

The SOP Class Extended Negotiation Sub-Item consists of a sequence of mandatory fields as defined by PS3.7. Table Y.5.1-2 defines the Service-class-application-information field for the C-MOVE and C-GET operations.

Table Y.5.1-2. SOP Class Extended Negotiation Sub-Item (Service-Class-Application-Information Field) - A-ASSOCIATE-AC

Item Bytes | Field Name | Description of Field
--- | --- | ---
1 | Unused | Reserved - shall not be tested.
2 | Enhanced Multi-Frame Image Conversion | This byte field defines whether or not the Attribute Query/Retrieve View (0008,0053) shall be used to adjust the view returned in queries to consider conversion to or from Enhanced Multi-Frame Images. It shall be encoded as an unsigned binary integer and shall use one of the following values 0 - Query/Retrieve View not supported 1 - Query/Retrieve View supported

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