KEY ACTIVITY - An activity that is considered of major significance. A key activity is sometimes referred to as a milestone activity. (November 1990) KEY EVENT SCHEDULE - A schedule comprised of key events or milestones. These events are generally critical accomplishments planned at time intervals throughout the project and used as a basis to monitor overall project performance. The format may be either network or bar chart and may contain minimal detail at a highly summarized level. This is often referred to as a milestone schedule. (June 2007) KEY EVENTS - Major events the achievement of which that are deemed to be critical to the execution of the project. A key event is sometimes referred to as a milestone. (June 2007) KEY PERFORMANCE - Performance that is critical to the project or a project system. See also: KEY PERFORMANCE INDICATORS (KPI). (June 2007) KEY PERFORMANCE INDICATORS (KPI) - Indicators that: 1) Are determined at process/project initiation and listed in order of priority; 2) Reflect directly on key process/project objectives \[goals\]; and 3) Provide basis for trade-off decisions made during execution. At process/project completion these KPIs: 1) Will be the most relevant measures to confirm process/project acceptability and its product by the process/project's stakeholders as being "successful"; and 2) Can be reasonably measured in some way, at some time, on some scale with some level of confidence. Syn.: KEY SUCCESS INDICATORS (KSI). (June 2007) KEY SUCCESS INDICATORS (KSI) - Syn.: KEY PERFORMANCE INDICATORS (KPI). (June 2007) KNOWN - A quantity or condition characterized by certainty. (December 2011) KNOWN-UNKNOWN - An identifiable quantity or value having variability or an identifiable condition lacking certainty. (December 2011)