A unified international method to capture, record, and report the information necessary for documenting the mechanical performance of harvesting machines and systems under specified conditions is presented. It provides a data collection method as a basis for evaluation of systems across international boundaries for better selection of machines, prior to bearing the expense of purchasing the system. An in depth study of a prototype skidder on steep terrain was conducted to test the practicality of the method. The study resulted in some modification of the been received indicating support and suggesting minimal changes. The recommendations of other reviewers will be incorporated in the final Field Manual. A microcomputer program for filing and editing the data collected in the field will be developed. / Doctor of Philosophy