Unstructured clinical data primarily consists of healthcare documents transcribed based on physician dictations where the physician dictates the entire encounter he had with a patient. There could be different elements of this document which are classified into various sections like History of Present Illness, Past Medical History, Past Surgical History, Current Medications, Allergies, Physical Examination, etc. These sections may be documented in different forms in different hospitals and different physicians.
e.g. History of Present Illness may be documented as HPI, Present Illness, Brief History etc