Definition In a data model, a one-dimensional chronon
is a non-decomposable
time interval
of some fixed, minimal duration. An n-dimensional chronon
is a non-decomposable region in n-dimensional time.
Important special types of chronons include
valid-time,
transaction-time,
and
bitemporal chronons.
Explanation Data models may represent a time line by a
sequence of non-decomposable, consecutive time intervals of identical duration.
These intervals are termed chronons. A data model will typically leave the
particular chronon duration unspecified, to be fixed later by the individual
applications, within the restrictions posed by the implementation of the data
model. Consecutive chronons may be grouped into larger segments, termed
granules. The addendum gives a precise definition of this term.
Previously Used Names
Instant,
moment, time quantum, time unit.
Discussion of Naming
"Instant"
and "moment" invite confusion between a point in the
continuous model and a non-decomposable unit in the discrete model
(-E8). Clocking
instruments invariably report the occurrence of
events
in terms of
time intervals,
not time "points." Hence, events, even so-called
"instantaneous" events, can best be measured as having occurred during
an interval (-E9).
"Time quantum" is precise, but is longer and more technical than
"chronon"
(-E2).
"Time unit" is perhaps less precise
(-E9).