This industry comprises establishments primarily engaged in providing expertise in the field of information technologies through one or more of the following activities: (1) writing, modifying, testing, and supporting software to meet the needs of a particular customer; (2) planning and designing computer systems that integrate computer hardware, software, and communication technologies; (3) on-site management and operation of clients' computer systems and/or data processing facilities; and (4) other professional and technical computer related advice and services. Illustrative Examples: Computer facilities management services Custom computer programming services Computer systems integration design services Computer hardware or software consulting services Software installation services Establishments primarily engaged in--