To recap, individual files in IDC buckets are instances of DICOM composite objects. The specific type of object is defined by the
SOPClassUID.Metadata included in a given object is captured by the Information Object Definition as a list of Information Entities. Object definition also contains the list of specific Information Modules for the individual IEs. Note that modules included in a given IE are object-specific, while list of attributes included in a given Information Module is fixed!