North American Industry Classification System:

541511 Custom Computer Programming Services
541513 Computer Facilities Management Services
541611 Admin and General Mgmt. Services
561110 Office Administrative Services
561210 Facilities Support Services
561320 Temporary Help Services
561330 Professional Employer Organizations
561612 Security Guards and Control Services
611710 Educational Support Services
561990 All Other Support Services
541990  All Other Prof, Scientific, and Tech Services