The ranking of leading causes of death depends largely on how causes are grouped. For example, cancer is the second leading cause of death. But if cancers were counted separately--lung cancer, breast cancer, etc.--their ranks would be lower. On the other hand, various communicable diseases are counted separately.
This choice of groupings was made by the National Center for Health Statistics, and we follow their tabulation lists. See Anderson, RN. "Deaths: Leading Causes for 2000," National Vital Statistics Reports, vol. 50, no. 16. Hyattsville, Maryland: National Center for Health Statistics, September 2002 for a complete list of the 50 rankable causes (Table A) and a description of how they were chosen (beginning on page 1).
The rankable causes in the death MICA are designated by "#". There are two instances in which a pair of causes together constitute a rankable cause. In those cases, each member of the pair is designated by "##". "Motor vehicle accidents" and "Other accidents and adverse effects" together constitute "Unintentional injury." Within "Other diseases (residual)" causes 44 and 45 together constitute "Nutritional deficiencies."