POCV and LVF
Beginner
Giving every part its own small wobble in speed. The wobbles are added up as odds, not all at their worst at once.
Novice
A way of handling manufacturing variation in timing. Each building block gets its own measured spread of delay, and the tool combines the spreads along a path statistically instead of assuming every gate is at its worst at the same time. LVF (Liberty Variation Format) is the format that stores those spreads in the cell library.
Expert
Parametric OCV: each cell arc has a mean delay and a standard deviation (sigma). Along a path the means add and the sigmas combine by root-sum-square, and the check is made at a chosen number of sigmas. LVF tables give sigma for delay, output transition and setup/hold constraints as functions of input slew and output load.
Explained in Signoff (Design Flow).
See also: On-chip variation (OCV), Statistical STA (SSTA).