Warning! The Value subsystem provides a superior mechanism for storing, recording, and working with fleeting and time-changing data. There are multiple problems with using Atoms for transient data, including: (a) it is CPU-intensive to create an Atom. Creating Values is much faster. (b) it is CPU-intensive to insert an Atom into the AtomSpace. Values are not stored in the atomsapce. There is no functional need for the indexing services that the AtomSpace provides, so its pointless to store fleeting data there, anyway. (c) it can become very difficult, sometimes impossible, to remove Atoms from the atomspace. This can happen when an Atom become a part of the outgoing set of another atom; in such a case, it would be illegal to delete the atom. For these three reasons, it is adviced to use Values instead and only use AtTimeLink if you really need it. See also SpaceServer for additional space-time management ideas.
AtTimeLink A T
Additionally a time domain may be used. The format is as follows
AtTimeLink A T D
where D is a TimeDomainNode.
AtTimeLink A T
could be seen as equivalent to
EvaluationLink PredicateNode "AtTime" ListLink A T
where the PredicateNode "AtTime" is specially used to represent timestamps.
In case T is a TimeIntervalLink, then
AtTimeLink A TimeIntervalLink TimeNode t1 TimeNode t2
is equivalent to
OrLink AtTimeLink A TimeNode t1 ... AtTimeLink A TimeNode t2 - 1
for the case where time is discrete. For more details, see Temporal Reasoning.