diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNode.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNode.java
index bc97bf1..bdaacd8 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNode.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNode.java
@@ -603,11 +603,6 @@
 	}
 
 	@Override
-	public boolean isMatchable() {
-		return nodeRole.isMatchable();
-	}
-
-	@Override
 	public boolean isNavigable() {
 		return nodeRole.isNavigable();
 	}
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNodeRole.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNodeRole.java
index 42aca4f..1298c89 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNodeRole.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractNodeRole.java
@@ -112,7 +112,7 @@
 	}
 
 	@Override
-	public boolean isMatchable() {
+	public boolean isLet() {
 		return false;
 	}
 
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractRegion.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractRegion.java
index 7426abe..6e20a27 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractRegion.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/AbstractRegion.java
@@ -145,7 +145,7 @@
 		}
 	}
 
-	public static final class IsComputedPredicate implements Predicate<@NonNull Node>
+	/*	public static final class IsComputedPredicate implements Predicate<@NonNull Node>
 	{
 		public static final @NonNull IsComputedPredicate INSTANCE = new IsComputedPredicate();
 
@@ -153,7 +153,7 @@
 		public boolean apply(@NonNull Node node) {
 			return node.isRealized();
 		}
-	}
+	} */
 
 	public static final class IsExpressionEdgePredicate implements Predicate<@NonNull Edge>
 	{
@@ -175,16 +175,6 @@
 		}
 	}
 
-	public static final class IsMatchableNodePredicate implements Predicate<@NonNull Node>
-	{
-		public static final @NonNull IsMatchableNodePredicate INSTANCE = new IsMatchableNodePredicate();
-
-		@Override
-		public boolean apply(@NonNull Node node) {
-			return node.isMatchable();
-		}
-	}
-
 	public static final class IsNavigableNodePredicate implements Predicate<@NonNull Node>
 	{
 		public static final @NonNull IsNavigableNodePredicate INSTANCE = new IsNavigableNodePredicate();
@@ -205,6 +195,26 @@
 		}
 	}
 
+	public static final class IsNewNodePredicate implements Predicate<@NonNull Node>
+	{
+		public static final @NonNull IsNewNodePredicate INSTANCE = new IsNewNodePredicate();
+
+		@Override
+		public boolean apply(@NonNull Node node) {
+			return node.isRealized() || node.isSpeculation();
+		}
+	}
+
+	public static final class IsOldNodePredicate implements Predicate<@NonNull Node>
+	{
+		public static final @NonNull IsOldNodePredicate INSTANCE = new IsOldNodePredicate();
+
+		@Override
+		public boolean apply(@NonNull Node node) {
+			return node.isConstant() || node.isLoaded() || node.isPredicated() || node.isSpeculated();
+		}
+	}
+
 	public static final class IsPatternNodePredicate implements Predicate<@NonNull Node>
 	{
 		public static final @NonNull IsPatternNodePredicate INSTANCE = new IsPatternNodePredicate();
@@ -255,16 +265,6 @@
 		}
 	}
 
-	public static final class IsRealizedOrSpeculationNodePredicate implements Predicate<@NonNull Node>
-	{
-		public static final @NonNull IsRealizedOrSpeculationNodePredicate INSTANCE = new IsRealizedOrSpeculationNodePredicate();
-
-		@Override
-		public boolean apply(@NonNull Node node) {
-			return node.isRealized() || node.isSpeculation();
-		}
-	}
-
 	public static final class IsRecursionEdgePredicate implements Predicate<@NonNull Edge>
 	{
 		public static final @NonNull IsRecursionEdgePredicate INSTANCE = new IsRecursionEdgePredicate();
@@ -966,16 +966,16 @@
 		SymbolNameBuilder s = null;
 		Set<@NonNull Node> bestToOneSubRegion = null;
 		Node bestNamingNode = null;
-		for (@NonNull Node node : getRealizedOrSpeculationNodes()) {
-			Set<@NonNull Node> toOneSubRegion = computeToOneSubRegion(new HashSet<@NonNull Node>(), node);
+		for (@NonNull Node newNode : getNewNodes()) {
+			Set<@NonNull Node> toOneSubRegion = computeToOneSubRegion(new HashSet<@NonNull Node>(), newNode);
 			if ((bestToOneSubRegion == null) || (toOneSubRegion.size() > bestToOneSubRegion.size())) {
 				bestToOneSubRegion = toOneSubRegion;
-				bestNamingNode = node;
+				bestNamingNode = newNode;
 			}
 			else if ((bestNamingNode != null) && (toOneSubRegion.size() == bestToOneSubRegion.size())) {
-				if (ClassUtil.safeCompareTo(bestNamingNode.getCompleteClass().getName(), node.getCompleteClass().getName()) > 0) {
+				if (ClassUtil.safeCompareTo(bestNamingNode.getCompleteClass().getName(), newNode.getCompleteClass().getName()) > 0) {
 					bestToOneSubRegion = toOneSubRegion;
-					bestNamingNode = node;
+					bestNamingNode = newNode;
 				}
 			}
 		}
@@ -1604,9 +1604,9 @@
 		return Iterables.filter(nodes, IsComposedNodePredicate.INSTANCE);
 	}
 
-	public final @NonNull Iterable<@NonNull Node> getComputedNodes() {
+	/*	public final @NonNull Iterable<@NonNull Node> getComputedNodes() {
 		return Iterables.filter(nodes, IsComputedPredicate.INSTANCE);
-	}
+	} */
 
 	/*	public final @NonNull Iterable<? extends Edge> getConsumedOrderingEdges() {
 		@SuppressWarnings("null")
@@ -1774,10 +1774,50 @@
 		return multiRegion.getMappingRegion(action);
 	}
 
-	@Override
+	/*	@Override
 	public final @NonNull Iterable<@NonNull Node> getMatchableNodes() {
+		Set<@NonNull Node> matchableNodes1 = Sets.newHashSet(getMatchableNodes1());
+		Set<@NonNull Node> matchableNodes2 = Sets.newHashSet(getMatchableNodes2());
+		if (!matchableNodes1.equals(matchableNodes2)) {
+			StringBuilder s = new StringBuilder();
+			Set<@NonNull Node> extraNodesSet = Sets.newHashSet(matchableNodes2);
+			CompilerUtil.removeAll(extraNodesSet, matchableNodes1);
+			for (@NonNull Node node : extraNodesSet) {
+				s.append("\n  extra: ");
+				s.append(node);
+			}
+			Set<@NonNull Node> missingEdgesSet = Sets.newHashSet(matchableNodes1);
+			missingEdgesSet.removeAll(matchableNodes2);
+			for (@NonNull Node node : missingEdgesSet) {
+				s.append("\n  missing: ");
+				s.append(node);
+			}
+			//			assert false : "Bad getMatchableNodes for " + this + s.toString();
+			System.out.println("Bad getMatchableNodes for " + this + s.toString());
+		}
+		return matchableNodes2;
+	}
+
+	private @NonNull Iterable<@NonNull Node> getMatchableNodes1() {
 		return Iterables.filter(nodes, IsMatchableNodePredicate.INSTANCE);
 	}
+	private @NonNull Iterable<@NonNull Node> getMatchableNodes2() {
+		List<@NonNull Node> matchableNodes = new ArrayList<>();
+		for (@NonNull Node node : getNodes()) {
+			if (!node.isRealized()) {
+				if (node.isTrue()) {
+					matchableNodes.add(node);
+				}
+				else if (node.isOperation()) {
+					matchableNodes.add(node);
+				}
+				else if (node.isPattern() && node.isClass()) {
+					matchableNodes.add(node);
+				}
+			}
+		}
+		return matchableNodes;
+	} */
 
 	@Override
 	public @NonNull MultiRegion getMultiRegion() {
@@ -1818,6 +1858,11 @@
 	//	}
 
 	@Override
+	public final @NonNull Iterable<@NonNull Node> getNewNodes() {
+		return Iterables.filter(nodes, IsNewNodePredicate.INSTANCE);
+	}
+
+	@Override
 	public @NonNull Collection<@NonNull Node> getNodes() {
 		return nodes;
 	}
@@ -1828,6 +1873,11 @@
 	}
 
 	@Override
+	public final @NonNull Iterable<@NonNull Node> getOldNodes() {
+		return Iterables.filter(nodes, IsOldNodePredicate.INSTANCE);
+	}
+
+	@Override
 	public @NonNull List<@NonNull DatumConnection> getOutgoingConnections() {			// FIXME cache
 		List<@NonNull DatumConnection> connections = new ArrayList<@NonNull DatumConnection>();
 		for (@NonNull Node node : getNodes()) {
@@ -1932,11 +1982,6 @@
 	}
 
 	@Override
-	public final @NonNull Iterable<@NonNull Node> getRealizedOrSpeculationNodes() {
-		return Iterables.filter(nodes, IsRealizedOrSpeculationNodePredicate.INSTANCE);
-	}
-
-	@Override
 	public final @NonNull Iterable<@NonNull Edge> getRecursionEdges() {
 		@NonNull Iterable<@NonNull Edge> filter = Iterables.filter(edges, IsRecursionEdgePredicate.INSTANCE);
 		return filter;
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/BasicMappingRegion.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/BasicMappingRegion.java
index ce7063d..2085b5a 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/BasicMappingRegion.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/BasicMappingRegion.java
@@ -521,30 +521,30 @@
 	}
 
 	public void registerConsumptionsAndProductions() {
-		for (@NonNull Node assignedNode : getComputedNodes()) {
-			ClassDatumAnalysis classDatumAnalysis = assignedNode.getClassDatumAnalysis();
-			classDatumAnalysis.addProduction(this, assignedNode);
+		for (@NonNull Node newNode : getNewNodes()) {
+			ClassDatumAnalysis classDatumAnalysis = newNode.getClassDatumAnalysis();
+			classDatumAnalysis.addProduction(this, newNode);
 			ClassDatum classDatum = classDatumAnalysis.getClassDatum();
 			for (@SuppressWarnings("null")@NonNull AbstractAction consumingAction : classDatum.getRequiredBy()) {
 				MappingRegion consumingRegion = multiRegion.getMappingRegion(consumingAction);
 				assert consumingRegion != null;
-				for (@NonNull Node consumingNode : consumingRegion.getMatchableNodes()) {
+				for (@NonNull Node consumingNode : consumingRegion.getOldNodes()) {
 					if (consumingNode.getCompleteClass() == classDatumAnalysis.getCompleteClass()) {		// FIXME inheritance
 						classDatumAnalysis.addConsumption(consumingRegion, consumingNode);
 					}
 				}
 			}
 		}
-		for (@NonNull Node predicatedNode : getMatchableNodes()) {
+		for (@NonNull Node predicatedNode : getOldNodes()) {
 			ClassDatumAnalysis classDatumAnalysis = predicatedNode.getClassDatumAnalysis();
 			classDatumAnalysis.addConsumption(this, predicatedNode);
 			ClassDatum classDatum = classDatumAnalysis.getClassDatum();
 			for (@SuppressWarnings("null")@NonNull AbstractAction introducingAction : classDatum.getProducedBy()) {
 				MappingRegion producingRegion = multiRegion.getMappingRegion(introducingAction);
 				assert producingRegion != null;
-				for (@NonNull Node assignedNode : producingRegion.getComputedNodes()) {
-					if (assignedNode.getCompleteClass() == classDatumAnalysis.getCompleteClass()) {		// FIXME inheritance
-						classDatumAnalysis.addProduction(producingRegion, assignedNode);
+				for (@NonNull Node newNode : producingRegion.getNewNodes()) {
+					if (newNode.getCompleteClass() == classDatumAnalysis.getCompleteClass()) {		// FIXME inheritance
+						classDatumAnalysis.addProduction(producingRegion, newNode);
 					}
 				}
 			}
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/MappingRegion.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/MappingRegion.java
index 0cabf1f..b96c548 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/MappingRegion.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/MappingRegion.java
@@ -16,7 +16,7 @@
 
 public interface MappingRegion extends Region
 {
-	@NonNull Iterable<@NonNull Node> getComputedNodes();
+	//	@NonNull Iterable<@NonNull Node> getComputedNodes();
 	@NonNull Iterable<@NonNull MappingAction> getMappingActions();
 	void writeDebugGraphs(@Nullable String context);
 }
\ No newline at end of file
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Node.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Node.java
index f516dc3..0b94bb8 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Node.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Node.java
@@ -158,15 +158,6 @@
 	boolean isLoaded();
 
 	/**
-	 * Return true if this node is part of the to-one navigation path that is matched as part of a mapping's predicate.
-	 *
-	 * Regions with conflicting isMatchable() nodes cannot be merged.
-	 *
-	 * ?? isConstant() || isLoaded() || isPredicated()
-	 */
-	boolean isMatchable();
-
-	/**
 	 * Return true if this node is part of the to-one navigation path that is navigated to determine the navigation heads.
 	 */
 	boolean isNavigable();
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/NodeRole.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/NodeRole.java
index 5f186db..0af4799 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/NodeRole.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/NodeRole.java
@@ -60,7 +60,7 @@
 
 	boolean isIterator();
 
-	boolean isMatchable();
+	boolean isLet();
 
 	boolean isNavigable();
 
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Nodes.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Nodes.java
index c3aee2f..1ec525f 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Nodes.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Nodes.java
@@ -358,7 +358,7 @@
 		}
 
 		@Override
-		public boolean isMatchable() {
+		public boolean isLet() {
 			return true;
 		}
 
@@ -387,11 +387,6 @@
 		}
 
 		@Override
-		public boolean isMatchable() {
-			return true;
-		}
-
-		@Override
 		public boolean isNull() {
 			return true;
 		}
@@ -484,11 +479,6 @@
 		}
 
 		@Override
-		public boolean isMatchable() {
-			return phase != Role.Phase.REALIZED;
-		}
-
-		@Override
 		public boolean isOperation() {
 			return true;
 		}
@@ -695,11 +685,6 @@
 		}
 
 		@Override
-		public boolean isMatchable() {
-			return isGuard();
-		}
-
-		@Override
 		public boolean isNavigable() {
 			return navigable == NavigableEnum.NAVIGABLE;
 		}
@@ -792,11 +777,6 @@
 		}
 
 		@Override
-		public boolean isMatchable() {
-			return true;
-		}
-
-		@Override
 		public boolean isPattern() {
 			return true;
 		}
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/QVTp2QVTs.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/QVTp2QVTs.java
index 1b1798b..e73bc39 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/QVTp2QVTs.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/QVTp2QVTs.java
@@ -187,7 +187,7 @@
 	}
 
 	/**
-	 * Return the nodes with region at which a suitably matching head og annother region might be merged.
+	 * Return the nodes with region at which a suitably matching head of another region might be merged.
 	 * The nodes must be bi-directionally one to one to respect 1:N trace node relationships.
 	 */
 	protected @NonNull Iterable<@NonNull Node> getMergeableNodes(@NonNull MappingRegion region) {
@@ -198,7 +198,7 @@
 		return mergeableNodes;
 	}
 	private void getMergeableNodes(@NonNull Set<@NonNull Node> mergeableNodes, @NonNull Node node) {
-		if (node.isMatchable() && node.isClass() && mergeableNodes.add(node)) {
+		if (isMergeable(node.getNodeRole()) && mergeableNodes.add(node)) {
 			for (@NonNull NavigationEdge edge : node.getNavigationEdges()) {
 				if (edge.getOppositeEdge() != null) {
 					getMergeableNodes(mergeableNodes, edge.getTarget());
@@ -206,6 +206,30 @@
 			}
 		}
 	}
+	private boolean isMergeable(@NonNull NodeRole nodeRole) {
+		if (nodeRole.isRealized() || nodeRole.isSpeculation()) {
+			return false;
+		}
+		if (!nodeRole.isClass()) {
+			return false;
+		}
+		if (nodeRole.isLet()) {
+			return true;
+		}
+		if (nodeRole.isNull()) {
+			return true;
+		}
+		if (nodeRole.isOperation()) {
+			return true;
+		}
+		if (nodeRole.isTrue()) {
+			return true;
+		}
+		if (nodeRole.isPattern()) {
+			return nodeRole.isGuard();
+		}
+		return false;
+	}
 
 	/**
 	 * The primary region in a GuardedRegion must be single-headed. It may be multiply-produced, e.g. recursed.
@@ -283,9 +307,9 @@
 						}
 					}
 				}
-				for (@NonNull Node assignedNode : secondaryRegion.getComputedNodes()) {
-					if (assignedNode.isClass()) {							// Ignore nulls, attributes
-						ClassDatumAnalysis consumingClassDatumAnalysis = assignedNode.getClassDatumAnalysis();
+				for (@NonNull Node newNode : secondaryRegion.getNewNodes()) {
+					if (newNode.isClass()) {							// Ignore nulls, attributes
+						ClassDatumAnalysis consumingClassDatumAnalysis = newNode.getClassDatumAnalysis();
 						if (toOneReachableClasses.add(consumingClassDatumAnalysis)) {
 							for (@NonNull MappingRegion consumingRegion : consumingClassDatumAnalysis.getConsumingRegions()) {
 								if (allConsumingRegions.add(consumingRegion)) {
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Region.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Region.java
index 0947ec4..9971d5f 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Region.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Region.java
@@ -102,11 +102,6 @@
 	@Nullable ScheduledRegion getInvokingRegion();
 	@NonNull List<@NonNull DatumConnection> getLoopingConnections();
 
-	/**
-	 * Return the nodes that are matched or evaluated by the region's predicate.
-	 */
-	@NonNull Iterable<@NonNull Node> getMatchableNodes();
-
 	@NonNull MultiRegion getMultiRegion();
 	@Override
 	@NonNull String getName();
@@ -115,6 +110,11 @@
 	 */
 	@NonNull Iterable<@NonNull Node> getNavigableNodes();
 	@NonNull Iterable<@NonNull NavigationEdge> getNavigationEdges();
+
+	/**
+	 * Return all nodes created by this region. i.e. Speculation or Realized nodes.
+	 */
+	@NonNull Iterable<@NonNull Node> getNewNodes();
 	/**
 	 * Return all the next connections from this region to another region.
 	 * Where this is a hierarchical region the connections are those from the hierarchical head to its immediate internal regions.
@@ -124,6 +124,11 @@
 	@NonNull Collection<@NonNull Node> getNodes();
 
 	/**
+	 * Return all nodes referenced by this region. i.e. Constant, Loaded, Predicated, Speculated nodes.
+	 */
+	@NonNull Iterable<@NonNull Node> getOldNodes();
+
+	/**
 	 * Return all connections from this (hierarchical) region to another (hierarchical) region.
 	 */
 	@NonNull Iterable<@NonNull DatumConnection> getOutgoingConnections();
@@ -134,7 +139,6 @@
 	//	@NonNull Iterable<@NonNull Node> getPredicatedOrSpeculatedNodes();
 	@NonNull Iterable<@NonNull Edge> getRealizedEdges();
 	@NonNull Iterable<@NonNull NavigationEdge> getRealizedNavigationEdges();
-	@NonNull Iterable<@NonNull Node> getRealizedOrSpeculationNodes();
 	@NonNull Iterable<@NonNull Edge> getRecursionEdges();
 	@NonNull List<@NonNull NodeConnection> getRootConnections();
 	@NonNull SchedulerConstants getSchedulerConstants();
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Role.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Role.java
index 714669a..7993532 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Role.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/Role.java
@@ -47,6 +47,8 @@
 		SPECULATION,	// Awaiting other mappings to speculate
 		SPECULATED,		// Known other mappings are speculating
 		OTHER			// Not known, nothing to do with mapping execution.
+		// NEW = REALIZED || SPECULATION
+		// OLD = CONSTANT || LOADED || PREDICATED || SPECULATED
 	};
 
 	/**
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/RootScheduledRegion.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/RootScheduledRegion.java
index d6abb70..83cba8c 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/RootScheduledRegion.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvtp2qvts/RootScheduledRegion.java
@@ -321,7 +321,7 @@
 		//	class is part of the input model and is not an internal convenience.
 		//
 		for (@NonNull Region region : getRegions()) {
-			for (@NonNull Node predicatedNode : region.getMatchableNodes()) {
+			for (@NonNull Node predicatedNode : region.getOldNodes()) {
 				if (!predicatedNode.isHead()) {
 					if (!predicatedNode.isLoaded() && !predicatedNode.isConstant() && !predicatedNode.isInternal()) {
 						if (!isOnlyCastOrRecursed(predicatedNode)) {			// FIXME Eliminate cast nodes
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvti/BasicRegion2Mapping.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvti/BasicRegion2Mapping.java
index 3e96c02..a42632b 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvti/BasicRegion2Mapping.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvti/BasicRegion2Mapping.java
@@ -1173,10 +1173,10 @@
 	}
 
 	private void createRealizedVariables() {
-		for (@NonNull Node node : region.getRealizedOrSpeculationNodes()) {
-			if (node.isPattern() && node.isClass()) {
+		for (@NonNull Node newNode : region.getNewNodes()) {
+			if (newNode.isPattern() && newNode.isClass()) {
 				OCLExpression constructor = null;
-				for (Edge edge : node.getIncomingEdges()) {
+				for (Edge edge : newNode.getIncomingEdges()) {
 					if (edge.isExpression()) {
 						Node sourceNode = edge.getSource();
 						if (sourceNode.isOperation()) {
@@ -1184,12 +1184,12 @@
 						}
 					}
 				}
-				ClassDatumAnalysis classDatumAnalysis = node.getClassDatumAnalysis();
+				ClassDatumAnalysis classDatumAnalysis = newNode.getClassDatumAnalysis();
 				BottomPattern bottomPattern = getArea(classDatumAnalysis).getBottomPattern();
-				RealizedVariable realizedVariable = QVTimperativeUtil.createRealizedVariable(getSafeName(node), classDatumAnalysis.getCompleteClass().getPrimaryClass());
+				RealizedVariable realizedVariable = QVTimperativeUtil.createRealizedVariable(getSafeName(newNode), classDatumAnalysis.getCompleteClass().getPrimaryClass());
 				realizedVariable.setOwnedInit(constructor);
 				bottomPattern.getRealizedVariable().add(realizedVariable);
-				Variable oldVariable = node2variable.put(node, realizedVariable);
+				Variable oldVariable = node2variable.put(newNode, realizedVariable);
 				assert oldVariable == null;
 			}
 		}
diff --git a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvts/splitter/BodyStage.java b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvts/splitter/BodyStage.java
index f144441..3379b91 100644
--- a/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvts/splitter/BodyStage.java
+++ b/plugins/org.eclipse.qvtd.compiler/src/org/eclipse/qvtd/compiler/internal/qvts2qvts/splitter/BodyStage.java
@@ -56,7 +56,7 @@
 		//		this.stages = Lists.newArrayList(stages);
 		//		this.visibleIteratedNodes = computedVisibleIteratedNodes(stages);
 		this.visibleIteratorNodes = computedVisibleIteratorNodes(stages);
-		this.realizedNodes = computeRealizedNodes();
+		this.realizedNodes = computeNewNodes();
 		//
 		//	Determine the nodes needed to realize the realized nodes.
 		//
@@ -142,6 +142,13 @@
 		return nodesList;
 	}
 
+	protected @NonNull Iterable<@NonNull Node> computeNewNodes() {
+		Region region = splitter.getRegion();
+		List<@NonNull Node> newNode = Lists.newArrayList(region.getNewNodes());
+		Collections.sort(newNode, NameUtil.NAMEABLE_COMPARATOR);
+		return newNode;
+	}
+
 	protected @NonNull Iterable<@NonNull Node> computeReachableNodes(@NonNull Iterable<@NonNull Node> requiredNodes) {
 		Set<@NonNull Node> reachableNodes = SplitterUtil.computeNavigableNodes(allHeadNodes);
 		//		assert reachableNodes.containsAll(requiredNodes);
@@ -153,13 +160,6 @@
 		return reachableNodesList;
 	}
 
-	protected @NonNull Iterable<@NonNull Node> computeRealizedNodes() {
-		Region region = splitter.getRegion();
-		List<@NonNull Node> nodes = Lists.newArrayList(region.getRealizedOrSpeculationNodes());
-		Collections.sort(nodes, NameUtil.NAMEABLE_COMPARATOR);
-		return nodes;
-	}
-
 	/**
 	 * The required nodes are the sources of all realized navigation edges, and the transitive source
 	 * of all computations terminating in a realized node.