"This report proposes a methodology for applying weighting factors to system effectiveness quantification expressions of mathematical models for multi-function situations. Since the circumstances for applying ""W"" and 'tu"" terms are almost unlimited@ no attempt 'is made to show all possible applications of these terms. Rather@ the basic principles are discussed and illustrated by simple examples in order to keep the focus on the principles for quantifying 11W11 and 'tu"". The methods that are used at lower levels of the mission-function hierarchical tree are equally valid at higher levels. Consequentlyi the extension of these basic methods to more complicated situations was deliberately excluded from the content of this report. PURPOSE The purpose of this report is to do the following: a. Extend the scope of the basic expression (Es = AJ.Xl) for system effectiveness to include paramet;ers needed in the quantification of multi-functioned and multi-missioned systems by means of terms for Essentiality (W) and Utilization (U). b. Define the essentiality and utilization terms. c. Reiterate the need to look at several hierarchical levels when quantifying system effectiveness. d. Provide some discussion on the use of weight factors in quantification. e. Show the relationship between functions and system elements (hardware@ software@ personnel@ etc.). f. Present several examples of quantification of multi-functioned and multi-missioned systems. "