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.
Notes: 1. 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 wildcard (wildcard match).
2. 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.
Notes: 1. The Conformance Statement of the SCP lists the Optional Matching Key Attributes which are supported for matching.
2. An SCU can not expect the SCP to support a match on an Optional Matching Key.