Sequences of events are represented in PDP++ by creating subgroups
within the main .events
group of an environment. Each sub group
should contain a set of events that define one discrete sequence of
related events. If the appropriate SequenceEpoch and Sequence
processes are used, they will access the GroupCount
and
GetGroup
functions on the environment (see section 11.1 Environments), which
will allow the epoch-level process to iterate over the groups
(sequences) in the environment, while the sequence process iterates over
the events within each group. The sequence-based processes are
discussed in section 12.6.1 Processes for Sequences of Events.