These fields identify the underlying causes of death as edited and audited by the National Center for Health Statistics (NCHS). From 1999-2006 there were up to 8 codes, and from 2007-2013 there are up to 20 codes.
Positions 1-4: Condition Code (ICD-10 code)
Note: Whenever there is a 4-position code, there is always an implied decimal after the 3rd position.
Position 5: Nature of Injury Flag (only for ICD-9 codes)
1 = the code in position 1-4 is a Nature of Injury ICD-9 code
0 = all other codes