"Cooperative purchasing", procurement conducted by, or on behalf of, more than 1 public procurement unit or by a public procurement unit with an external procurement activity.
"External procurement activity", (a) a public agency not located in the commonwealth which would qualify as a public procurement unit; (b) buying by the United States government.
"Local public procurement unit", (a) a public agency not located in the commonwealth which would qualify as a public procurement unit; (b) buying by the United States government.
"Public procurement unit", a local public procurement unit or a state public procurement unit.
"State public procurement unit", the offices of the chief procurement officers and any other purchasing agency of the commonwealth or any other state.