# 12 - MOEs, MOPs and TPMs
Let's start by defining these acronyms: - MOEs: Measures Of Effectiveness - MOPs: Measures Of Performance - TPMs: Technical Performance Mesures Following a recent discussion on this topic, I've come to realize that there is a lot of confusion around these concepts, so let's try to bring some clarification! MOEs, which are stated from the acquirer (customer/user) viewpoint, are the acquirer's key indicators of achiving the needs for performance, suitability and affordability across the life cycle. The MOEs are used to validate the system at each stage of the design process and provide insight into some of the more subjective qualities desired by the acquirer that are not, or can not, be captured by hard requirements. Many of the "ilities" are used in MOEs where, for example, it may be very difficult to generate a shall statement on operability, but operability nevertheless remains an important characteristic. MOPs measure attributes considered as important to e...