3.9 DICOM Service Class Definitions
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## 3.9 DICOM Service Class Definitions

The following definitions are commonly used in this Part of the DICOM Standard:

Classic Image Storage SOP Class : an Image Storage SOP Class that is defined by an IOD that stores a single frame and defines the majority of the Attributes in the top-level Data Set.

Combined Print Image : a pixel matrix created by superimposing an image and an overlay, the size of which is defined by the smallest rectangle enclosing the superimposed image and overlay.

DICOM Information Model : an Entity-Relationship diagram that is used to model the relationships between the Information Object Definitions representing classes of Real-World Objects defined by the DICOM Application Model.

DICOM Application Model : an Entity-Relationship diagram used to model the relationships between Real-World Objects that are within the area of interest of the DICOM Standard.

Enhanced Image Storage SOP Class : an Image Storage SOP Class that is defined by an IOD that stores multiple frames and defines the majority of the Attributes in Functional Group Sequences.

Legacy Converted Enhanced Image Storage SOP Class : a modality-specific Enhanced Image Storage SOP Class that is defined by an IOD that defines only generic Functional Group Sequences, which does not require information that is not present in Classic Image Storage SOP Class Instances, and is intended for storage of converted Classic Image Storage SOP Class Instances when there is insufficient information to use a True Enhanced Image Storage SOP Class.

Meta Service-Object Pair (SOP) Class : a pre-defined set of SOP Classes that may be associated under a single SOP for the purpose of negotiating the use of the set with a single item.

Performed Procedure Step SOP Class : any SOP Class that encodes the details about the performance of a procedure step.

Performed Procedure Step SOP Instance : an instance of a Performed Procedure Step SOP Class. Note that all UPS instances are instances of the UPS Push SOP Class, which is capable of encoding details about the performance of a procedure step (in addition to details about the scheduled procedure step) and thus qualify as an instance of a Performed Procedure Step SOP Class.

Preformatted Grayscale Image : an image where all annotation, graphics, and grayscale transformations (up to and including the VOI LUT) expected in the printed image have been burnt in or applied before being sent to the SCP. It is a displayable image where the polarity of the intended display is specified by Photometric Interpretation (0028,0004).

Preformatted Color Image : an image where all annotation, graphics, and color transformations expected in the printed image have been burnt in or applied before being sent to the SCP.

Real-World Activity : that which exists in the real world that pertains to specific area of information processing within the area of interest of the DICOM Standard. Such a Real-World Activity may be represented by one or more computer information metaphors called SOP Classes.

Real-World Object : that which exists in the real world upon which operations may be performed that are within the area of interest of the DICOM Standard. Such a Real-World Object may be represented through a computer information metaphor called a SOP Instance.

Related General SOP Class : a SOP Class that is related to another SOP Class as being more generalized in terms of behavior defined in the standard, and that may be used to identically encode an instance with the same Attributes and values, other than the SOP Class UID. In particular, this may be the SOP Class from which a Specialized SOP Class (see PS3.2) is derived.

Service Class User : the role played by a DICOM Application Entity (DIMSE-Service-User) that invokes operations and performs notifications on a specific Association.

Service Class Provider : the role played by a DICOM Application Entity (DIMSE-Service-User) that performs operations and invokes notifications on a specific Association.

Service Class : a collection of SOP Classes and/or Meta SOP Classes that are related in that they are described together to accomplish a single application.

Service-Object Pair (SOP) Class : the union of a specific set of DIMSE Services and one related Information Object Definition (as specified by a Service Class Definition) that completely defines a precise context for communication of operations on such an object or notifications about its state.

Service-Object Pair (SOP) Instance : a concrete occurrence of an Information Object that is managed by a DICOM Application Entity and may be operated upon in a communication context defined by a specific set of DIMSE Services (on a network or interchange media). A SOP Instance is persistent beyond the context of its communication.

True Enhanced Image Storage SOP Class : a modality-specific Enhanced Image Storage SOP Class that is defined by an IOD that defines modality-specific Functional Group Sequences, Attributes and sets of values, and is intended for creation by acquisition devices.

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