Baseline clock; Clock; Time-segment clock
In the discrete model of time, a time-line clock is defined as a set of physical clocks coupled with some specification of when each physical clock is authoritative. Each chronon in a time-line clock is a chronon (or a regular division of a chronon) in an identified, underlying physical clock. The time-line clock switches from one physical clock to the next at a synchronization point. A synchronization point correlates two, distinct physical clock measurements.
A time-line clock is the clock for (concrete) times stored in a temporal database. A time-line clock glues together a sequence of physical clocks to provide a consistent, clear semantics for a time line. Since the range of most physical clocks is limited, a time-line clock is usually composed of many physical clocks. For instance, a tree-ring clock can only be used to date past events, and the atomic clock can only be used to date events since the 1950s....