Time coordinate

provides a time specification for its corresponding knowledge item

The time coordinate is a k-coordinate of each k-object.

do k-coordinates also apply to relations?

Its meaning depends on the object. In general it means the time of validity of the object. Some examples:

• An event happens at an instant of time.
• A meeting happens at a (for instance, weekly) recurring time interval.

Evaluation algorithm

• We want to determine whether an instant of time is within a specified time.
• Given an instant, we want to get the next/previous matching instant wihting a recurring time specifiation.