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.