In defining a microeconomic system two distinct component elements will be identified: an environment and an institution. The environment consists of a list of N economic agents {l,..., N}, a list of K + 1 commodities (including resources) {O, l,..., K}, and certain characteristics of each agent … Hence, a microeconomic environment is defined by the collection of characteristics e = (e',..., e).

p. 925. - "Microeconomic systems as an experimental science," 1982