A dependency between two tasks.
:type is one of :finish_start, :start_start, :finish_finish or
:start_finish. :lag is in the :time_units passed to MpxjEx.read/2
(seconds by default) and :lag_units is the unit the lag was entered in.
Summary
Types
@type type() :: :finish_start | :start_start | :finish_finish | :start_finish