PS 3.2 - 2009
Page 16
- Standard -
3.11.2 Standard SOP Class
A SOP Class defined in the DICOM Standard that is used in an implementation with no modifications.
3.11.3 Standard Extended SOP Class
A SOP Class defined in the DICOM Standard extended in an implementation with additional Type 3
Attributes. The additional Attributes may either be drawn from the Data Dictionary in PS 3.6, or may be
Private Attributes. The semantics of the related Standard SOP Class shall not be modified by the
additional Type 3 Attributes when absent. Therefore, the Standard Extended SOP Class utilizes the
same UID as the related Standard SOP Class.
Note: IODs from a Standard Extended SOP Class may be freely exchanged between DICOM implementations
since implementations unfamiliar with the additional Type 3 Attributes would simply ignore them.
3.11.4 Specialized SOP Class
A SOP Class derived from a Standard SOP Class that has been specialized in an implementation by
additional Type 1, 1C, 2, 2C, or 3 Attributes, by enumeration of specific permitted values for Attributes, or
by enumeration of specific permitted Templates. The additional Attributes may either be drawn from the
Data Dictionary in PS 3.6, or may be Private Attributes. The enumeration of permitted Attribute values or
Templates shall be a subset of those permitted in the related Standard SOP Class. Since the semantics
of the related Standard SOP Class may be modified by the additional Attributes, a Specialized SOP Class
utilizes a Privately Defined UID which differs from the UID for the related Standard SOP Class.
Notes: 1. Since a Specialized SOP Class has a different UID than a Standard or Standard Extended SOP Class,
other DICOM implementations may not recognize the Specialized SOP Class. Because of this limitation,
a Specialized SOP Class should only be used when a Standard or Standard Extended SOP Class would
not be appropriate. Before different implementations can exchange Instances in a Specialized SOP
Class, the implementations must agree on the UID, content (in particular the additional Type 1, 1C, 2,
and 2C Attributes), and semantics of the Specialized SOP Class. A Specialized SOP Class may be used
to create a new or experimental SOP Class that is closely related to a Standard SOP Class.
2. The Association Negotiation for a Specialized SOP Class may include a SOP Class Common
Extended Negotiation Sub-Item (as defined in PS 3.7) for identification of the Service Class and of the
Related General SOP Class from which it was specialized. This may allow a receiving application,
without prior agreement on the Specialized SOP Class IOD, to process Instances of that class as if they
were instances of a Related General SOP Class.
3.11.5 Private SOP Class
A SOP Class that is not defined in the DICOM Standard, but is published in an implementation's
Conformance Statement.
Note: Since a Private SOP Class is not defined in the DICOM Standard, other DICOM implementations may
not recognize the Private SOP Class. Because of this limitation, a Private SOP Class should only be
used when a Standard or Standard Extended SOP Class would not be appropriate. In order for different
implementations to exchange Instances in a Private SOP Class, the implementations must agree on the
UID, content (in particular the Type 1, 1C, 2, and 2C Attributes), and semantics of the Private SOP Class.
A Private SOP class may be used to create a totally new or experimental SOP Class.
3.11.6 Standard Attribute
An Attribute defined in the Data Dictionary in PS 3.6.
3.11.7 Private Attribute
An Attribute that is not defined in the DICOM Standard.