3.3. Time-slices
Each task has associated with it “time-slice” metadata values related to the local timesteps::
the task%t(:), task%dt(:), task%time, float values, and the task%it
and task%iit(:) integer values that support a rotating buffer view of the time values.
The timestep metadata values are accessed twice: First in list_t%check_nbors() and
check_ready(), which uses task_t%time and task_t%dtime to determine if the nbors
of a task are sufficiently advanced in time to consider the task ready to update.
Later, when the guard zone values are downloaded, the first (nt-1) values
of task_t%t(:) and task_t%dt(:) are used to find out how to interpolate
in the time-slice values, to fill guard zones at the required, specific times