42 Computer software design, computer programming or maintenance of computer software; introduction and explanation relating to performance, operation, etc of computers, automobiles and other machines that require high levels of personal knowledge, skill or experience of the operators to meet the purposed; accuracy in operating them; computer rental including central processing units, programmed-data-encoded electronic circuits, magnetic disks, magnetic tapes and other peripheral equipment; designing of machines, apparatus, instruments including their parts or systems composed of such machines, apparatus and instruments; designing; meteorological information; providing employment information