Which of These Actually Happened First SKEW
A phone crosses a border. A laptop is four minutes fast. A recorder never had its clock set. Sort those three by the time column and the order you get is fiction.
The devices
The declared zone is what the device says its times are in, which is a separate fact from whether the clock is right. The tick is the smallest unit it records: a recorder that writes whole minutes cannot tell you anything finer, and that limit is carried through to every answer.
The anchors
An anchor is one real event that two devices both recorded: a call in the handset log and in the switch record, a person through a door on the access system and on the camera. One anchor fixes the difference between two clocks exactly; a chain of them reaches everything the chain touches, and nothing else.
The events
The clocks, solved
Whether the anchors agree
What changed
The timeline, corrected
The working
Questions people ask about SKEW