CheckConstraints are used for different use cases

Table: CheckConstraint

Sub Element Usage Card Type Description Note
  CheckDirection optional 0..1 CheckDirectionEnumeration For CHECK CONSTRAINTs associated with PATH LINKs, the direction in which the check applies. Forwards = from/to, backwards = to/from. For Check constraints associated with an external ENTRANCE, forwards is into the SITE, backwards is out of the SITE. We usually only use one direction.
  CheckProcess optional 0..1 CheckProcessTypeEnumeration Type of process that may occur at CHECK CONSTRAINT. Only a given subset is allowed
  Congestion optional 0..1 CongestionEnumeration Type of crowding that may slow use of CHECK CONSTRAINT.  
  delays expected 0..1 delays Delays for CHECK CONSTRAINT .process.  
+ CheckConstraintDelay expected 1..1 CheckConstraintDelay Time penalty associated with a CHECK CONSTRAINT. We currently only model delays
++ AverageDelay expected 0..1 xsd:duration Average duration expected to pass through Check.  
++ MaximumLikelyDelay optional 0..1 xsd:duration Maximum duration expected to pass through CHECK CONSTRAINT.