// Get inter-pass and intra-pass constraints
List<Element> elements = XMLUtil.selectNodes(orderingConstraintsNode, "./SplitPass|./WithinPass");
for (Element constraintElement : elements) {
// Create the selectors which determine which detectors are
// involved in the constraint
DetectorFactorySelector earlierSelector = getConstraintSelector(constraintElement, plugin, "Earlier");
DetectorFactorySelector laterSelector = getConstraintSelector(constraintElement, plugin, "Later");
// Create the constraint
DetectorOrderingConstraint constraint = new DetectorOrderingConstraint(earlierSelector, laterSelector);
// Keep track of which constraints are single-source