zbieżność usterek(The point at which the rate of fixed bugs exceeds the rate of found bugs. Bug convergence is a visible indication that the team is making progress against the active bug count. It is a sign that the project end is within reach)
zero nawrotu usterek(" The first point in time after a milestone (typically code complete) that there are no active bugs accepted by the triage meetings that are older a specified amount of time (typically between 3 hours and 3 days). It is referred to as bounce because bugs checked in can cause regressions and these regressions can cause the number of bugs to "bounce" back up from zero.")