The lexicon of the top500 ( The Encyclopedia for Classification Codes ) explains the codes and definitions in the world of economical classifications.
NAICS Code 9231 Administration of Human Resource Programs
The NAICS Code 9231 is described as
Administration of Human Resource Programs It belongs to the code group
NAICS Code 923 Administration of Human Resource Programs
To this Code "9231" belongs the sub codes
NAICS Code 92311: Administration of Education Programs
NAICS Code 92312: Administration of Public Health Programs
NAICS Code 92313: Administration of Human Resource Programs (except Education, Public Health, and Veterans' Affairs Programs)
NAICS Code 92314: Administration of Veterans' Affairs