When I open a dicom file and save it all tags from the 0008 group are gone!
DicomFile df = new DicomFile(fname);
df.Load(DicomReadOptions.Default);
df.DataSet[DicomTags.StudyId].SetStringValue("Jonas was here!");
bool ok = df.Save(@"C:\cc_test.dcm", DicomWriteOptions.CalculateGroupLengths);