A relationship between an activity and a input-constraint whereby the constraint needs to be satified in order for the activity to start.
(Inherited-Facet-Value Minimum-Slot-Cardinality Epml-Activity Epml-Specified-Pre-Condition 0) (Inherited-Facet-Value Slot-Value-Type Epml-Activity Epml-Specified-Pre-Condition Epml-Pre-Condition)