The material in this subseries was sent to us by Mr. Joseph P. Loftus Jr. who, at the time these documents were created, was the Chief of the Technical Planning Office (AT). The documents consist of presentation material, notes, correspondence and reports related to background studies done on the STS User Charge System. The material runs from 1957 through 1980. It is grouped into several sections: user charge correspondence and background material (1957-1979), presentation material (1974-80), and OPRA (Operations Phase Resource Analysis) related documents (1974-75).