HIPAA defines de-identified data as:
Data that does not identify an individual
Data that has the 18 categories of direct identifiers removed
Data that allows no reason to believe it can be used, alone or in combination with other information to identify an individual
Coded data is not considered to be de-identified data. Additionally, the following unofficial MHS Quasi-identifiers must be excluded from the data set:
Age, duty location, race, rank, ethnicity, pay grade, training site, unit identification code (UIC)