The Worklist Information Model is identified by the SOP Class negotiated at Association establishment time. The SOP Class is composed of both an Information Model and a DIMSE-C Service Group.
Information Model Definitions for standard SOP Classes of the Worklist Service Class are defined in this Annex. A Worklist Information Model Definition contains:
an Entity-Relationship Model Definition
a Key Attributes Definition;
Basic Worklist Information Models consist of a single level, that includes all Matching Key Attributes and all Return Key Attributes, which may be sent from the SCU to the SCP in the request and whose values are expected to be returned from the SCP to the SCU in each of the responses (or worklist items). The Matching Key Attribute values in the request specify the worklist items that are to be returned in the responses. All Key Attributes (the Matching Key Attributes and the Return Key Attributes) in the request determine which Attribute values are returned in the responses for that worklist.
A Worklist Item has a one-to-one relationship with the real-world object defining the root for the Basic Worklist Information Model. In addition the worklist item is related to a number of other objects from the real-world model. Each of these real-world objects is represented by a hierarchy of entities organized in an (internal) Entity-Relationship Model.
Attributes are defined for each entity in the internal Entity-Relationship Model. An Identifier in a C-FIND request shall contain values to be matched against the Attributes of the Entities in a Worklist Information Model. For any worklist request, the set of entities for which Attributes are returned, shall be determined by the set of Matching and Return Key Attributes specified in the Identifier.
All Attributes of entities in a Worklist Information Model shall be specified both as a Matching Key Attribute (either required or optional) and as a Return Key Attribute.
The Matching Key Attributes are Keys, which select worklist items to be included in a requested Worklist.
A Basic Worklist Management SCP shall support matching based on values of all Required Matching Key Attributes of the C-FIND request. Multiple entities may match a given value for a Required Key.
If an SCP manages an entity with an unknown Attribute value (i.e., zero length), the unknown value shall fail to match any Matching Key value.
Even though there is no means to perform matching on such entities, they may be queried as a Return Key Attribute using a C-FIND request with a zero length value (universal match) or by a single wild card (wild card match).
An SCU may choose to supply any subset of Required Matching Key Attributes.
In the Worklist Information Model, a set of Attributes may be defined as Optional Matching Key Attributes. Optional Matching Key Attributes contained in the Identifier of a C-FIND request may induce two different types of behavior depending on support for matching by the SCP. If the SCP
does not support matching on the Optional Matching Key Attribute, then the Optional Matching Key Attribute shall be ignored for matching but shall be processed in the same manner as a Return Key Attribute.
supports matching of the Optional Matching Key Attribute, then the Optional Matching Key Attribute shall be processed in the same manner as a Required Matching Key.
The Conformance Statement of the SCP lists the Optional Matching Key Attributes that are supported for matching.
An SCU can not expect the SCP to support a match on an Optional Matching Key.
The values of Return Key Attributes to be retrieved with the Worklist are specified with zero-length (universal matching) in the C-FIND request. SCPs shall support Return Key Attributes defined by a Worklist Information Model according to the Data Element Type (1, 1C, 2, 2C, 3) as defined in PS3.5.
Every Matching Key Attribute shall also be considered as a Return Key Attribute. Therefore the C-FIND response shall contain in addition to the values of the requested Return Key Attributes the values of the requested Matching Key Attributes.
The Conformance Statement of the SCP lists the Return Key Attributes of Type 3, which are supported.
An SCU may choose to supply any subset of Return Key Attributes.
An SCU can not expect to receive any Type 3 Return Key Attributes.
Return Key Attributes with VR of SQ may be specified either with zero-length or with the zero-length item in the sequence.
The following types of matching, which are defined by the Query/Retrieve Service Class in Annex C may be performed on Matching Key Attributes in the Basic Worklist Service Class. Different Matching Key Attributes may be subject for different matching types. The Worklist Information Model defines the type of matching for each Required Matching Key Attribute. The Conformance Statement of the SCP shall define the type of matching for each Optional Matching Key Attribute. The types of matching are:
Single Value Matching
List of UID Matching
Wild Card Matching
Range Matching
Sequence Matching
The following type of matching, which is defined by the Query/Retrieve Service Class in Annex C of this Part shall be performed on Return Key Attributes in the Basic Worklist Service Class.
Universal Matching
See Section C.2.2.2 and subsections for specific rules governing of Matching Key Attribute encoding for and performing of different types of matching.
The Specific Character Set (0008,0005) Attribute and/or the Timezone Offset From UTC (0008,0201) Attribute may be present in the Identifier but are never matched, i.e., they are not considered Matching Key Attributes. See Section C.2.2.2 for details.
Single value matching of Attributes with Person Name Value Representation may be affected by extended negotiation of fuzzy semantic matching of person names.