diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java
new file mode 100644
index 00000000000..a2e41c70274
--- /dev/null
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java
@@ -0,0 +1,112 @@
+/*******************************************************************************
+ * Copyright (c) 2007 Symbian Software Ltd. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Andrew Ferguson (Symbian) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.internal.index.tests;
+
+import java.util.regex.Pattern;
+
+import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IBinding;
+import org.eclipse.cdt.core.index.IIndexFileLocation;
+import org.eclipse.cdt.core.index.IIndexLinkage;
+import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.internal.core.index.IIndexFragment;
+import org.eclipse.cdt.internal.core.index.IIndexFragmentBinding;
+import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
+import org.eclipse.cdt.internal.core.index.IIndexFragmentInclude;
+import org.eclipse.cdt.internal.core.index.IIndexFragmentName;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IProgressMonitor;
+
+/**
+ * An empty index fragment implementation
+ * @since 4.0.1
+ */
+public class EmptyIndexFragment implements IIndexFragment {
+	public void acquireReadLock() throws InterruptedException {}
+
+	public IIndexFragmentBinding adaptBinding(IBinding binding)
+			throws CoreException {
+		return null;
+	}
+
+	public IIndexFragmentBinding adaptBinding(IIndexFragmentBinding proxy)
+			throws CoreException {
+		return null;
+	}
+
+	public IIndexFragmentBinding findBinding(IASTName astName) throws CoreException {
+		return null;
+	}
+
+	public IIndexFragmentBinding[] findBindings(Pattern[] patterns,
+			boolean isFullyQualified, IndexFilter filter,
+			IProgressMonitor monitor) throws CoreException {
+		return IIndexFragmentBinding.EMPTY_INDEX_BINDING_ARRAY;
+	}
+
+	public IIndexFragmentBinding[] findBindings(char[][] names,
+			IndexFilter filter, IProgressMonitor monitor) throws CoreException {
+		return IIndexFragmentBinding.EMPTY_INDEX_BINDING_ARRAY;
+	}
+
+	public IIndexFragmentBinding[] findBindingsForPrefix(char[] prefix,
+			boolean filescope, IndexFilter filter, IProgressMonitor monitor)
+			throws CoreException {
+		return IIndexFragmentBinding.EMPTY_INDEX_BINDING_ARRAY;
+	}
+
+	public IIndexFragmentInclude[] findIncludedBy(IIndexFragmentFile file)
+			throws CoreException {
+		return IIndexFragmentInclude.EMPTY_FRAGMENT_INCLUDES_ARRAY;
+	}
+
+	public IIndexFragmentName[] findNames(IIndexFragmentBinding binding,
+			int flags) throws CoreException {
+		return IIndexFragmentName.EMPTY_NAME_ARRAY;
+	}
+
+	public long getCacheHits() {
+		return 0;
+	}
+
+	public long getCacheMisses() {
+		return 0;
+	}
+
+	public IIndexFragmentFile getFile(IIndexFileLocation location)
+			throws CoreException {
+		return null;
+	}
+
+	public long getLastWriteAccess() {
+		return 0;
+	}
+
+	public IIndexLinkage[] getLinkages() {
+		return IIndexLinkage.EMPTY_INDEX_LINKAGE_ARRAY;
+	}
+
+	public String getProperty(String key) throws CoreException {
+		if(IIndexFragment.PROPERTY_FRAGMENT_ID.equals(key)) {
+			return "org.eclipse.cdt.internal.core.index.EmptyIndexFragment"; //$NON-NLS-1$
+		}
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_ID.equals(key)) {
+			return "org.eclipse.cdt.internal.core.index.EmptyIndexFragmentFormat"; //$NON-NLS-1$
+		}
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION.equals(key)) {
+			return "0"; //$NON-NLS-1$
+		}
+		return null;
+	}
+
+	public void releaseReadLock() {}
+	public void resetCacheCounters() {}
+}
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexProviderManagerTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexProviderManagerTest.java
index 0859add59cf..8d2df68f928 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexProviderManagerTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexProviderManagerTest.java
@@ -11,10 +11,6 @@
 package org.eclipse.cdt.internal.index.tests;
 
 import java.io.File;
-import java.lang.reflect.Array;
-import java.lang.reflect.InvocationHandler;
-import java.lang.reflect.Method;
-import java.lang.reflect.Proxy;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -55,6 +51,7 @@ import org.eclipse.cdt.core.testplugin.CProjectHelper;
 import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.provider.IIndexFragmentProvider;
 import org.eclipse.cdt.internal.core.index.provider.IndexProviderManager;
+import org.eclipse.cdt.internal.core.pdom.PDOM;
 import org.eclipse.cdt.internal.core.pdom.PDOMManager;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IProjectDescription;
@@ -63,6 +60,7 @@ import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.NullProgressMonitor;
 import org.eclipse.core.runtime.QualifiedName;
+import org.eclipse.osgi.service.resolver.VersionRange;
 
 /**
  * Example usage and test for IIndexProvider
@@ -76,6 +74,14 @@ public class IndexProviderManagerTest extends IndexTestBase {
 	final static Class DP5= Providers.Dummy5.class;
 	final static Class[] DPS= new Class[] {DP4, DP2, DP1, DP3, DP5};
 	
+	/*
+	 * Fictional compatibility ranges for testing
+	 */
+	final static VersionRange VERSION_400= new VersionRange("36");
+	final static VersionRange VERSION_401= new VersionRange("[36,37]");
+	final static VersionRange VERSION_405= new VersionRange("[37,39]");
+	final static VersionRange VERSION_502= new VersionRange("[89,91]");
+	
 	final CCorePlugin core= CCorePlugin.getDefault();
 	
 	public IndexProviderManagerTest() {
@@ -86,6 +92,11 @@ public class IndexProviderManagerTest extends IndexTestBase {
 		return suite(IndexProviderManagerTest.class);
 	}
 
+	protected void tearDown() throws Exception {
+		IndexProviderManager ipm= ((PDOMManager)CCorePlugin.getIndexManager()).getIndexProviderManager();
+		ipm.reset(); ipm.startup();
+	}
+	
 	public void testProvider_SimpleLifeCycle_200958() throws Exception {
 		for(int i=0; i<DPS.length; i++)
 			DPT.reset(DPS[i]);
@@ -170,6 +181,136 @@ public class IndexProviderManagerTest extends IndexTestBase {
 		}
 	}
 	
+	public void testVersioning_IncompatibleIgnored() throws Exception {
+		IndexProviderManager ipm= ((PDOMManager)CCorePlugin.getIndexManager()).getIndexProviderManager();
+		
+		ICProject cproject = null;
+		try {
+			cproject= CProjectHelper.createCCProject("IndexFactoryConfigurationUsageTest", IPDOMManager.ID_NO_INDEXER);
+			IProject project= cproject.getProject();
+			
+			
+			MockState mockState = new MockState(cproject);
+			mockState.setConfig(MockState.REL_V1_ID);
+			
+			IIndexProvider provider1= new IIndexFragmentProvider() {
+				IIndexFragment[] fragments= new IIndexFragment[] {
+					new MockPDOM("contentID.contentA", "36"),
+					new MockPDOM("contentID.contentA", "37"),
+					new MockPDOM("contentID.foo", "90"),
+					new MockPDOM("contentID.bar", "91"),
+					new MockPDOM("contentID.baz", "89")
+				};
+				public IIndexFragment[] getIndexFragments(ICConfigurationDescription config) {
+					return fragments;
+				}
+				public boolean providesFor(ICProject project) throws CoreException {
+					return true;
+				}
+			};
+			IIndexProvider provider2= new IIndexFragmentProvider() {
+				IIndexFragment[] fragments= new IIndexFragment[] {
+						new MockPDOM("contentID.baz", "90"),
+						new MockPDOM("contentID.contentA", "38"),
+				};
+				public IIndexFragment[] getIndexFragments(ICConfigurationDescription config) {
+					return fragments;
+				}
+				public boolean providesFor(ICProject project) throws CoreException {
+					return true;
+				}
+			};
+			
+			CCorePlugin.getIndexManager().joinIndexer(8000, NPM); // ensure IPM is called only once under test conditions
+			setExpectedNumberOfLoggedNonOKStatusObjects(3); // foo, bar and baz have no compatible fragments available
+			
+			ipm.reset(VERSION_405); ipm.startup();
+			ipm.addIndexProvider(provider1);  ipm.addIndexProvider(provider2);
+			
+			IIndexFragment[] actual = ipm.getProvidedIndexFragments(mockState.getCurrentConfig());
+			assertEquals(1, actual.length);
+			assertFragmentPresent("contentID.contentA", "38", actual);
+		} finally {
+			if(cproject!=null) {
+				cproject.getProject().delete(IResource.FORCE | IResource.ALWAYS_DELETE_PROJECT_CONTENT, new NullProgressMonitor());
+			}
+		}
+	}
+	
+	public void testVersioning_NoCompatibleVersionsFound() throws Exception {
+		IndexProviderManager ipm= ((PDOMManager)CCorePlugin.getIndexManager()).getIndexProviderManager();
+		
+		ICProject cproject = null;
+		try {
+			cproject= CProjectHelper.createCCProject("IndexFactoryConfigurationUsageTest", IPDOMManager.ID_NO_INDEXER);
+			IProject project= cproject.getProject();
+			
+			
+			MockState mockState = new MockState(cproject);
+			mockState.setConfig(MockState.REL_V1_ID);
+			
+			IIndexProvider provider1= new IIndexFragmentProvider() {
+				IIndexFragment[] fragments= new IIndexFragment[] {
+					new MockPDOM("contentID.contentA", "36"),
+					new MockPDOM("contentID.contentA", "37"),
+					new MockPDOM("contentID.foo", "90"),
+					new MockPDOM("contentID.bar", "91"),
+					new MockPDOM("contentID.baz", "89")
+				};
+				public IIndexFragment[] getIndexFragments(ICConfigurationDescription config) {
+					return fragments;
+				}
+				public boolean providesFor(ICProject project) throws CoreException {
+					return true;
+				}
+			};
+			IIndexProvider provider2= new IIndexFragmentProvider() {
+				IIndexFragment[] fragments= new IIndexFragment[] {
+					new MockPDOM("contentID.contentA", "41"),
+				};
+				public IIndexFragment[] getIndexFragments(ICConfigurationDescription config) {
+					return fragments;
+				}
+				public boolean providesFor(ICProject project) throws CoreException {
+					return true;
+				}
+			};
+			
+			CCorePlugin.getIndexManager().joinIndexer(8000, NPM); // ensure IPM is called only once under test conditions
+			setExpectedNumberOfLoggedNonOKStatusObjects(1); // contentA has no compatible fragments available
+			
+			ipm.reset(VERSION_502); ipm.startup();
+			ipm.addIndexProvider(provider1);  ipm.addIndexProvider(provider2);
+			
+			IIndexFragment[] actual = ipm.getProvidedIndexFragments(mockState.getCurrentConfig());
+			assertEquals(3, actual.length);
+			assertFragmentPresent("contentID.foo", "90", actual);
+			assertFragmentPresent("contentID.bar", "91", actual);
+			assertFragmentPresent("contentID.baz", "89", actual);
+		} finally {
+			if(cproject!=null) {
+				cproject.getProject().delete(IResource.FORCE | IResource.ALWAYS_DELETE_PROJECT_CONTENT, new NullProgressMonitor());
+			}
+		}
+	}
+	
+	private void assertFragmentPresent(String id, String version, IIndexFragment[] fragments) throws Exception {
+		for(int i=0; i<fragments.length; i++) {
+			IIndexFragment candidate= fragments[i];
+			String cid= null, csver= null;
+			try {
+				candidate.acquireReadLock();
+				cid= candidate.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+				csver= candidate.getProperty(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION);
+			} finally {
+				candidate.releaseReadLock();
+			}
+			if(id.equals(cid) && version.equals(csver))
+				return;
+		}
+		fail("Fragment matching (id="+id+",version="+version+") was not present");
+	}
+	
 	public void testIndexFactoryConfigurationUsage() throws Exception {
 		IIndex index;
 		
@@ -372,10 +513,9 @@ class MockStateIndexProvider implements IIndexProvider {
 }
 
 class MockStateIndexFragmentProvider extends MockStateIndexProvider implements IIndexFragmentProvider {
-	IIndexFragment[] fragments;
-	int[] mcounts;
-	boolean invert;
-
+	private boolean invert;
+	final IIndexFragment[] fragments;
+	
 	public void invert() {
 		invert = !invert;
 	}
@@ -384,9 +524,8 @@ class MockStateIndexFragmentProvider extends MockStateIndexProvider implements I
 		super(cproject);
 
 		fragments = new IIndexFragment[MockState.states.size()];
-		mcounts = new int[MockState.states.size()];
 		for(int i=0; i<MockState.states.size(); i++) {
-			fragments[i] = createMockFragment(mcounts, i);
+			fragments[i] = new MockPDOM("mock.test.index."+System.identityHashCode(this)+"."+i, ""+PDOM.CURRENT_VERSION);
 		}
 	}
 
@@ -401,22 +540,6 @@ class MockStateIndexFragmentProvider extends MockStateIndexProvider implements I
 			return new IIndexFragment[] {fragments[index]};
 		}
 	}
-
-	public IIndexFragment createMockFragment(final int[] mcounts, final int index) {
-		return (IIndexFragment) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[] {IIndexFragment.class}, new InvocationHandler(){
-			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
-				Object result = null;
-				if(method.getReturnType().isArray()) {
-					result = Array.newInstance(method.getReturnType().getComponentType(), 0);
-				}
-				if(method.getName().equals("toString")) {
-					return "[Mock index fragment #"+index+"]";
-				}
-				mcounts[index]++;
-				return result;
-			}
-		});
-	}
 }
 
 class MockConfig implements ICConfigurationDescription {
@@ -589,3 +712,29 @@ class MockState {
 	}
 }
 
+class MockPDOM extends EmptyIndexFragment {
+	String id;
+	String version;
+	
+	MockPDOM(String id, String version) {
+		this.id= id;
+		this.version= version;
+	}
+	
+	public String getProperty(String propertyName) throws CoreException {
+		if(IIndexFragment.PROPERTY_FRAGMENT_ID.equals(propertyName)) {
+			return id;
+		}
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_ID.equals(propertyName)) {
+			return PDOM.FRAGMENT_PROPERTY_VALUE_FORMAT_ID;
+		}
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION.equals(propertyName)) {
+			return version;
+		}
+		return null;
+	}
+	
+	public String toString() {
+		return "[Mock index fragment "+id+"."+System.identityHashCode(this)+"]";
+	}
+}
\ No newline at end of file
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java
index e33a81980a3..c79d3bf8407 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java
@@ -52,16 +52,33 @@ public interface IIndexFragment {
 	final int FIND_ALL_OCCURENCES = 		  IIndex.FIND_ALL_OCCURENCES;
 	
 	/**
-	 * Property key constant for the fragment ID. The fragment ID should uniquely identify the fragments usage within
+	 * Property key for the fragment ID. The fragment ID should uniquely identify the fragments usage within
 	 * a logical index.
+	 * @since 4.0
 	 */
 	public static final String PROPERTY_FRAGMENT_ID= "org.eclipse.cdt.internal.core.index.fragment.id"; //$NON-NLS-1$
+
+	/**
+	 * Property key for the fragment format ID. The fragment format ID should uniquely identify a format of an index fragment
+	 * up to version information. That is, as a particular format changes version its ID should remain the same.
+	 * @since 4.0.1
+	 */
+	public static final String PROPERTY_FRAGMENT_FORMAT_ID= "org.eclipse.cdt.internal.core.index.fragment.format.id"; //$NON-NLS-1$
+	
+	/**
+	 * Property key for the fragment format's version. Version numbers belonging to the same format (identified by format ID) should be
+	 * comparable with each other. The version scheme exposed should be compatible with the OSGi framework's
+	 * version scheme - i.e. it should be successfully parsed by org.osgi.framework.Version.parseVersion(String). A null value
+	 * for this property is interpreted as Version(0.0.0)
+	 * @since 4.0.1
+	 */
+	public static final String PROPERTY_FRAGMENT_FORMAT_VERSION= "org.eclipse.cdt.internal.core.index.fragment.format.version"; //$NON-NLS-1$
 	
 	/**
 	 * Returns the file for the given location. May return <code>null</code>, if no such file exists.
-	 * This method may only return files that are actually managed by this fragement.
+	 * This method may only return files that are actually managed by this fragment.
 	 * @param location the IIndexFileLocation representing the location of the file
-	 * @return the file for the location
+	 * @return the file for the location, or <code>null</code> if the file is not present in the index
 	 * @throws CoreException
 	 */
 	IIndexFragmentFile getFile(IIndexFileLocation location) throws CoreException;
@@ -167,11 +184,17 @@ public interface IIndexFragment {
 	
 	/**
 	 * Read the named property in this fragment. All fragments are expected to return a non-null value for 
-	 *    <pre>PROPERTY_FRAGMENT_ID</pre>
+	 *    <ul>
+	 *    <li>PROPERTY_FRAGMENT_ID</li>
+	 *    <li>PROPERTY_FRAGMENT_FORMAT_ID</li>
+	 *    <li>PROPERTY_FRAGMENT_FORMAT_VERSION</li>
+	 *    </ul>
 	 * @param key a case-sensitive identifier for a property, or null
 	 * @return the value associated with the key, or null if either no such property is set, or the specified key was null
 	 * @throws CoreException
 	 * @see IIndexFragment#PROPERTY_FRAGMENT_ID
+	 * @see IIndexFragment#PROPERTY_FRAGMENT_FORMAT_ID
+	 * @see IIndexFragment#PROPERTY_FRAGMENT_FORMAT_VERSION
 	 */
 	public String getProperty(String propertyName) throws CoreException;
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/IndexProviderManager.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/IndexProviderManager.java
index aadc4ed83eb..0a134b6dc9e 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/IndexProviderManager.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/IndexProviderManager.java
@@ -13,11 +13,12 @@ package org.eclipse.cdt.internal.core.index.provider;
 
 import java.text.MessageFormat;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.index.provider.IIndexProvider;
@@ -28,31 +29,70 @@ import org.eclipse.cdt.core.model.ICElement;
 import org.eclipse.cdt.core.model.ICElementDelta;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.model.IElementChangedListener;
+import org.eclipse.cdt.core.parser.util.ArrayUtil;
 import org.eclipse.cdt.core.settings.model.ICConfigurationDescription;
 import org.eclipse.cdt.internal.core.index.IIndexFragment;
+import org.eclipse.cdt.internal.core.pdom.PDOM;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.IExtensionPoint;
 import org.eclipse.core.runtime.IExtensionRegistry;
+import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Platform;
-
+import org.eclipse.core.runtime.Status;
+import org.eclipse.osgi.service.resolver.VersionRange;
+import org.osgi.framework.Version;
 
 /**
  * The IndexProviderManager is responsible for maintaining the set of index
  * fragments contributed via the CIndex extension point.
  * <p>
  * It is an internal class, and is public only for testing purposes.
+ * @since 4.0
+ */
+/*
+ * For bug 196338, the role of this class was extended. It now has responsibility to
+ * look at the pool of fragments available depending on their IDs, and select the most appropriate.
+ * The following rules are applied
+ * 	(i) If its not compatible, don't use it
+ *  (ii) If multiple are compatible, pick the latest
+ *  
+ * A warning is logged if a fragment is contributed which is incompatible, and for which there is
+ * no compatible equivalent.
  */
 public final class IndexProviderManager implements IElementChangedListener {
-	public static final String READ_ONLY_PDOM_PROVIDER= "ReadOnlyPDOMProvider"; //$NON-NLS-1$
-	private IIndexFragmentProvider[] allProviders= {};
-	private Map provisionMap= new HashMap();
+	private static final String ELEMENT_RO_PDOMPROVIDER= "ReadOnlyPDOMProvider"; //$NON-NLS-1$
+	private static final String ATTRIBUTE_CLASS = "class"; //$NON-NLS-1$
+
+	private IIndexFragmentProvider[] allProviders;
+	private Map/*<List,Boolean>*/ provisionMap;
+	private Set/*<String>*/ compatibleFragmentUnavailable;
+	private VersionRange pdomVersionRange;
 	
 	public IndexProviderManager() {
+		reset();
+	}
+
+	/**
+	 * <b>Note: This method should not be called by clients for purposes other than testing</b>
+	 */
+	public void reset() {
+		reset(new VersionRange("["+PDOM.MIN_SUPPORTED_VERSION+','+PDOM.CURRENT_VERSION+']')); //$NON-NLS-1$
 	}
 	
+	/**
+	 * <b>Note: This method should not be called by clients for purposes other than testing</b>
+	 * @param pdomVersionRange
+	 */
+	public void reset(VersionRange pdomVersionRange) {
+		this.allProviders= new IIndexFragmentProvider[0];
+		this.provisionMap= new HashMap();
+		this.pdomVersionRange= pdomVersionRange;
+		this.compatibleFragmentUnavailable= new HashSet();
+	}
+
 	public void startup() {
 		List providers = new ArrayList();
 		IExtensionRegistry registry = Platform.getExtensionRegistry();
@@ -63,8 +103,9 @@ public final class IndexProviderManager implements IElementChangedListener {
 			try {
 				IConfigurationElement[] ce = extension.getConfigurationElements();
 				for(int j=0; j<ce.length; j++) {
-					if(ce[j].getName().equals(READ_ONLY_PDOM_PROVIDER)) {
-						IIndexProvider provider = (IIndexProvider) ce[j].createExecutableExtension("class"); //$NON-NLS-1$
+					if(ce[j].getName().equals(ELEMENT_RO_PDOMPROVIDER)) {
+						IIndexProvider provider = (IIndexProvider) ce[j].createExecutableExtension(ATTRIBUTE_CLASS);
+
 						if(provider instanceof IReadOnlyPDOMProvider) {
 							provider = new ReadOnlyPDOMProviderBridge((IReadOnlyPDOMProvider)provider);
 							providers.add(provider);
@@ -90,29 +131,126 @@ public final class IndexProviderManager implements IElementChangedListener {
 	 * registered IIndexProvider objects for the specified project, and
 	 * for the current state of the project.
 	 * Order in the array is not significant.
-	 * @param project
+	 * @param config
 	 * @return the array of IIndexFragment objects for the current state
 	 */
 	public IIndexFragment[] getProvidedIndexFragments(ICConfigurationDescription config) throws CoreException {
-		List preResult = new ArrayList();
+		Map id2fragment = new HashMap();
 
 		IProject project= config.getProjectDescription().getProject();
 		for(int i=0; i<allProviders.length; i++) {
 			try {
 				if(providesForProject(allProviders[i], project)) {
-					preResult.addAll(Arrays.asList(allProviders[i].getIndexFragments(config)));
+					IIndexFragment[] fragments= allProviders[i].getIndexFragments(config);
+					for(int j=0; j<fragments.length; j++) {
+						try {
+							processCandidate(id2fragment, fragments[j]);
+						} catch(InterruptedException ie) {
+							CCorePlugin.log(ie); // continue with next candidate
+						} catch(CoreException ce) {
+							CCorePlugin.log(ce); // continue with next candidate
+						}
+					}		
 				}
 			} catch(CoreException ce) {
-				CCorePlugin.log(ce);
+				CCorePlugin.log(ce); // move to next provider
 			}
 		}
 
-		IIndexFragment[] result = (IIndexFragment[]) preResult.toArray(new IIndexFragment[preResult.size()]);
-		return result;
+		// Make log entries for any fragments which have no compatible equivalents
+		List preresult= new ArrayList();
+		for(Iterator i=id2fragment.entrySet().iterator(); i.hasNext(); ) {
+			Map.Entry entry= (Map.Entry) i.next();
+			if(entry.getValue()==null) {
+				String key= (String) entry.getKey();
+				if(!compatibleFragmentUnavailable.contains(key)) {
+					String msg= MessageFormat.format(
+						Messages.IndexProviderManager_NoCompatibleFragmentsAvailable,
+						new Object[]{key}
+					);
+					IStatus status= new Status(IStatus.WARNING, CCorePlugin.PLUGIN_ID, IStatus.WARNING, msg, null);
+					CCorePlugin.log(status);
+					compatibleFragmentUnavailable.add(key);
+				}
+			} else {
+				preresult.add(entry.getValue());
+			}
+		}
+		return (IIndexFragment[]) preresult.toArray(new IIndexFragment[preresult.size()]);
+	}
+	
+	/**
+	 * Returns the version range supported by the format identified by the specified formatID.
+	 * @param formatID
+	 */
+	private VersionRange getCurrentlySupportedVersionRangeForFormat(String formatID) {
+		/*
+		 * TODO - at the point we support alternate IIndexFragment implementations, this method will need
+		 * to be altered to lookup version ranges for the contributed format via an extension point.
+		 */
+		if(!PDOM.FRAGMENT_PROPERTY_VALUE_FORMAT_ID.equals(formatID)) {
+			throw new IllegalArgumentException("Non-PDOM formats are currently unsupported"); //$NON-NLS-1$
+		}
+		return pdomVersionRange;
+	}
+	
+	/**
+	 * Examines the candidate fragment, adding it to the map (using its fragment id as key) if
+	 * it compatible with the current run-time, and it is better than any existing fragments for
+	 * the same fragment id.
+	 * @param id2fragment
+	 * @param candidate
+	 */
+	private void processCandidate(Map id2fragment, IIndexFragment candidate) throws InterruptedException, CoreException {
+		String cid= null, csver= null, cformatID= null;
+		try {
+			candidate.acquireReadLock();
+			cid= candidate.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			csver= candidate.getProperty(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION);
+			cformatID= candidate.getProperty(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_ID);							
+		} finally {
+			candidate.releaseReadLock();
+		}
+		assert cid!=null && csver!=null && cformatID!=null;
+
+		Version cver= Version.parseVersion(csver); // illegal argument exception
+		IIndexFragment existing= (IIndexFragment) id2fragment.get(cid);
+		
+		if(getCurrentlySupportedVersionRangeForFormat(cformatID).isIncluded(cver)) {
+			if(existing != null) {
+				String esver= null, eformatID= null;
+				try {
+					existing.acquireReadLock();
+					esver= existing.getProperty(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION);
+					eformatID= existing.getProperty(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_ID);
+				} finally {
+					existing.releaseReadLock();
+				}
+				
+				if(eformatID.equals(cformatID)) {	
+					Version ever= Version.parseVersion(esver); // illegal argument exception
+					if(ever.compareTo(cver) < 0) {
+						id2fragment.put(cid, candidate);
+					}
+				} else {
+					/*
+					 * In future we could allow users to specify
+					 * how format (i.e. PDOM -> custom IIndexFragment implementation)
+					 * changes are coped with.  
+					 */
+				}
+			} else {
+				id2fragment.put(cid, candidate);
+			}
+		} else {
+			if(existing==null) {
+				id2fragment.put(cid, null); // signifies candidate is unusable
+			}
+		}
 	}
 
 	/**
-	 * This is only public for test purposes
+	 * <b>Note: This method should not be called for purposes other than testing</b>
 	 * @param provider
 	 */
 	public void addIndexProvider(IIndexProvider provider) {
@@ -131,6 +269,20 @@ public final class IndexProviderManager implements IElementChangedListener {
 		allProviders = newAllProviders;
 	}
 
+	/**
+	 * Removes the specified provider by object identity
+	 * <b>Note: This method should not be called for purposes other than testing</b>
+	 * @param provider
+	 */	
+	public void removeIndexProvider(IIndexProvider provider) {
+		ArrayUtil.remove(allProviders, provider);
+		if(allProviders[allProviders.length-1]==null) {
+			IIndexFragmentProvider[] newAllProviders = new IIndexFragmentProvider[allProviders.length-1];
+			System.arraycopy(allProviders, 0, newAllProviders, 0, allProviders.length-1);
+			allProviders= newAllProviders;
+		}
+	}
+
 	private boolean providesForProject(IIndexProvider provider, IProject project) {
 		List key = new ArrayList();
 		key.add(provider);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/Messages.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/Messages.java
index fe1cf9091f3..f448a387f74 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/Messages.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/Messages.java
@@ -15,6 +15,7 @@ import org.eclipse.osgi.util.NLS;
 public class Messages extends NLS {
 	private static final String BUNDLE_NAME = "org.eclipse.cdt.internal.core.index.provider.messages"; //$NON-NLS-1$
 	public static String IndexProviderManager_0;
+	public static String IndexProviderManager_NoCompatibleFragmentsAvailable;
 	public static String OfflinePDOMProviderBridge_UnsupportedUsage;
 	public static String PDOMCache_VersionTooOld;
 	static {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/PDOMCache.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/PDOMCache.java
index 382a7a0821b..7b56eef267c 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/PDOMCache.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/PDOMCache.java
@@ -12,11 +12,8 @@
 package org.eclipse.cdt.internal.core.index.provider;
 
 import java.io.File;
-import java.text.MessageFormat;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.Map;
-import java.util.Set;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.index.IIndexLocationConverter;
@@ -29,17 +26,15 @@ import org.eclipse.core.runtime.IPath;
  * Internal singleton map maintained for non-project PDOM objects
  */
 class PDOMCache {
-	private Map/*<File, PDOM>*/ path2pdom; // gives the pdom for a particular path
-	private Set/*<File>*/ versionMismatch;
-	
+	private Map/*<File, PDOM>*/ path2pdom; // gives the PDOM for a particular path
+
 	private static PDOMCache singleton;
 	private static Object singletonMutex = new Object();
 
 	private PDOMCache() {
 		this.path2pdom = new HashMap();
-		this.versionMismatch = new HashSet();
 	}
-	
+
 	/**
 	 * Returns the instance of the cache
 	 * @return
@@ -54,48 +49,30 @@ class PDOMCache {
 	}
 
 	/**
-	 * Returns the mapped pdom for the path specified, if such a pdom is not already known about
+	 * Returns the mapped PDOM for the path specified, if such a pdom is not already known about
 	 * then one is created using the location converter specified. 
 	 * @param path
 	 * @param converter
-	 * @return a pdom instance or null if the pdom version was too old
+	 * @return a PDOM instance or null if the PDOM version was too old
 	 */
 	public PDOM getPDOM(IPath path, IIndexLocationConverter converter) {
 		PDOM result= null;
 		File file = path.toFile();
 
-		if(!versionMismatch.contains(file)) {
-			synchronized(path2pdom) {
-				if(path2pdom.containsKey(file)) {
-					result = (PDOM) path2pdom.get(file);
+		synchronized(path2pdom) {
+			if(path2pdom.containsKey(file)) {
+				result = (PDOM) path2pdom.get(file);
+			}
+			if(result==null) {
+				try {
+					result = new PDOM(file, converter, LanguageManager.getInstance().getPDOMLinkageFactoryMappings());
+					path2pdom.put(file, result);
+				} catch(CoreException ce) {
+					CCorePlugin.log(ce);
 				}
-				if(result==null) {
-					try {
-						result = new PDOM(file, converter, LanguageManager.getInstance().getPDOMLinkageFactoryMappings());
-
-						result.acquireReadLock();
-						try {
-							if(!result.isSupportedVersion()) {
-								versionMismatch.add(file);
-								String msg= MessageFormat.format(Messages.PDOMCache_VersionTooOld, new Object[] {file});
-								CCorePlugin.log(msg);
-								return null;
-							} else {
-								path2pdom.put(file, result);
-							}
-						} finally {
-							result.releaseReadLock();
-						}
-					} catch(CoreException ce) {
-						CCorePlugin.log(ce);
-					} catch(InterruptedException ie) {
-						CCorePlugin.log(ie);
-					}
-				}
-
 			}
 		}
 
 		return result;
 	}
-}
+}
\ No newline at end of file
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/messages.properties b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/messages.properties
index a0e7f83d6c8..87063621795 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/messages.properties
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/provider/messages.properties
@@ -11,3 +11,4 @@
 IndexProviderManager_0=Ignoring unrecognized implementation of IIndexProvider contributed by {0}
 OfflinePDOMProviderBridge_UnsupportedUsage=Unsupported usage of IOfflinePDOMProvider
 PDOMCache_VersionTooOld=External index (PDOM) version is not supported: {0}
+IndexProviderManager_NoCompatibleFragmentsAvailable=No compatible index fragment found for fragment id: {0}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
index 47fe62dd09c..65df7b909e0 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
@@ -73,47 +73,60 @@ import org.eclipse.core.runtime.Status;
 public class PDOM extends PlatformObject implements IIndexFragment, IPDOM {
 	protected Database db;
 
+	/**
+	 * Identifier for PDOM format
+	 * @see IIndexFragment#PROPERTY_FRAGMENT_FORMAT_ID
+	 */
+	public static final String FRAGMENT_PROPERTY_VALUE_FORMAT_ID= "org.eclipse.cdt.internal.core.pdom.PDOM"; //$NON-NLS-1$
+	
 	public static final int CURRENT_VERSION = 37;
 	public static final int MIN_SUPPORTED_VERSION= 36;
 	public static final int MIN_VERSION_TO_WRITE_NESTED_BINDINGS_INDEX= 37;	// to be removed in 4.1
-	// 0 - the beginning of it all
-	// 1 - first change to kick off upgrades
-	// 2 - added file inclusions
-	// 3 - added macros and change string implementation
-	// 4 - added parameters in C++
-	// 5 - added types and restructured nodes a bit
-	// 6 - function style macros.
-	// 7 - class key
-	// 8 - enumerators
-	// 9 - base classes
-	// 10 - typedefs, types on C++ variables
-	// 11 - changed how members work
-	// 12 - one more change for members (is-a list -> has-a list)
-	// 13 - CV-qualifiers, storage class specifiers, function/method annotations
-	// 14 - added timestamps for files (bug 149571)
-	// 15 - fixed offsets for pointer types and qualifier types and PDOMCPPVariable (bug 160540). 
-	// 16 - have PDOMCPPField store type information, and PDOMCPPNamespaceAlias store what it is aliasing
-	// 17 - use single linked list for names in file, adds a link to enclosing definition name.
-	// 18 - distinction between c-unions and c-structs.
-    // 19 - alter representation of paths in the pdom (162172)
-	// 20 - add pointer to member types, array types, return types for functions
-	// 21 - change representation of paths in the pdom (167549)
-	// 22 - fix inheritance relations (167396)
-	// 23 - types on c-variables, return types on c-functions
-	// 24 - file local scopes (161216)
-	// 25 - change ordering of bindings (175275)
-	// 26 - add properties storage
-	// 27 - templates: classes, functions, limited nesting support, only template type parameters
-	// 28 - templates: class instance/specialization base classes
-	// 29 - includes: fixed modeling of unresolved includes (180159)
-	// 30 - templates: method/constructor templates, typedef specializations
-	// 31 - macros: added file locations
-	// 32 - support stand-alone function types (181936)
-	// 33 - templates: constructor instances
-	// 34 - fix for base classes represented by qualified names (183843)
-	// 35 - add scanner configuration hash-code (62366)
-	// 36 - changed chunk size back to 4K (184892)
-	// 37 - added index for nested bindings (189811), compatible with version 36.
+	
+	/* 
+	 * PDOM internal format history
+	 * 
+	 *    #x# = the version was used in an official release
+	 * 
+	 *   0 - the beginning of it all
+	 *   1 - first change to kick off upgrades
+	 *   2 - added file inclusions  
+	 *   3 - added macros and change string implementation
+	 *   4 - added parameters in C++
+	 *   5 - added types and restructured nodes a bit
+	 *   6 - function style macros	 
+	 * # 7#- class key - <<CDT 3.1>>
+	 *   8 - enumerators
+	 *   9 - base classes
+	 *  10 - typedefs, types on C++ variables
+	 * #11#- changed how members work - <<CDT 3.1.1>>, <<CDT 3.1.2>>
+	 *  12 - one more change for members (is-a list -> has-a list)
+	 *  13 - CV-qualifiers, storage class specifiers, function/method annotations
+	 *  14 - added timestamps for files (bug 149571)
+	 *  15 - fixed offsets for pointer types and qualifier types and PDOMCPPVariable (bug 160540). 
+	 *  16 - have PDOMCPPField store type information, and PDOMCPPNamespaceAlias store what it is aliasing
+	 *  17 - use single linked list for names in file, adds a link to enclosing definition name.
+	 *  18 - distinction between c-unions and c-structs.
+	 *  19 - alter representation of paths in the pdom (162172)
+	 *  20 - add pointer to member types, array types, return types for functions
+	 *  21 - change representation of paths in the pdom (167549)
+	 *  22 - fix inheritance relations (167396)
+	 *  23 - types on c-variables, return types on c-functions
+	 *  24 - file local scopes (161216)
+	 *  25 - change ordering of bindings (175275)
+	 *  26 - add properties storage
+	 *  27 - templates: classes, functions, limited nesting support, only template type parameters
+	 *  28 - templates: class instance/specialization base classes
+	 *  29 - includes: fixed modeling of unresolved includes (180159)
+	 *  30 - templates: method/constructor templates, typedef specializations
+	 *  31 - macros: added file locations
+	 *  32 - support stand-alone function types (181936)
+	 *  33 - templates: constructor instances
+	 *  34 - fix for base classes represented by qualified names (183843)
+	 *  35 - add scanner configuration hash-code (62366)
+	 * #36#- changed chunk size back to 4K (184892) - <<CDT 4.0>>
+	 * #37#- added index for nested bindings (189811), compatible with version 36 - <<CDT 4.0.1>>
+	 */
 	
 	public static final int LINKAGES = Database.DATA_AREA;
 	public static final int FILE_INDEX = Database.DATA_AREA + 4;
@@ -760,6 +773,12 @@ public class PDOM extends PlatformObject implements IIndexFragment, IPDOM {
 	}
 
 	public String getProperty(String propertyName) throws CoreException {
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_ID.equals(propertyName)) {
+			return FRAGMENT_PROPERTY_VALUE_FORMAT_ID;
+		}
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION.equals(propertyName)) {
+			return ""+db.getVersion(); //$NON-NLS-1$
+		}
 		return new DBProperties(db, PROPERTIES).getProperty(propertyName);
 	}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
index 158c70591d2..508bde45d3b 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
@@ -25,6 +25,7 @@ import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorMacroDefinition;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexLocationConverter;
+import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
 import org.eclipse.cdt.internal.core.index.IWritableIndexFragment;
 import org.eclipse.cdt.internal.core.index.IWritableIndex.IncludeInformation;
@@ -88,11 +89,18 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		return result;
 	}
 	
+	/*
+	 * (non-Javadoc)
+	 * @see org.eclipse.cdt.internal.core.index.IWritableIndexFragment#setProperty(java.lang.String, java.lang.String)
+	 */
 	public void setProperty(String propertyName, String value) throws CoreException {
+		if(IIndexFragment.PROPERTY_FRAGMENT_FORMAT_ID.equals(propertyName) 
+		|| IIndexFragment.PROPERTY_FRAGMENT_FORMAT_VERSION.equals(propertyName)) {
+			throw new IllegalArgumentException("Property "+value+" may not be written to"); //$NON-NLS-1$ //$NON-NLS-2$
+		}
 		new DBProperties(db, PROPERTIES).setProperty(propertyName, value);
 	}
 	
-
 	/**
 	 * Use the specified location converter to update each internal representation of a file location.
 	 * The file index is rebuilt with the new representations. Individual PDOMFile records are unmoved so
diff --git a/doc/org.eclipse.cdt.doc.isv/guide/dom/index/prebuiltVersioning.html b/doc/org.eclipse.cdt.doc.isv/guide/dom/index/prebuiltVersioning.html
new file mode 100644
index 00000000000..dc319b7243c
--- /dev/null
+++ b/doc/org.eclipse.cdt.doc.isv/guide/dom/index/prebuiltVersioning.html
@@ -0,0 +1,350 @@
+<html xmlns:v="urn:schemas-microsoft-com:vml"
+xmlns:o="urn:schemas-microsoft-com:office:office"
+xmlns:w="urn:schemas-microsoft-com:office:word"
+xmlns="http://www.w3.org/TR/REC-html40">
+
+<head>
+<meta http-equiv=Content-Type content="text/html; charset=windows-1252">
+<meta name=ProgId content=Word.Document>
+<meta name=Generator content="Microsoft Word 10">
+<meta name=Originator content="Microsoft Word 10">
+<link rel=File-List href="prebuiltVersioning_files/filelist.xml">
+<link rel=Edit-Time-Data href="prebuiltVersioning_files/editdata.mso">
+<!--[if !mso]>
+<style>
+v\:* {behavior:url(#default#VML);}
+o\:* {behavior:url(#default#VML);}
+w\:* {behavior:url(#default#VML);}
+.shape {behavior:url(#default#VML);}
+</style>
+<![endif]-->
+<title>Versioning pre-built indexes</title>
+<!--[if gte mso 9]><xml>
+ <w:WordDocument>
+  <w:Zoom>80</w:Zoom>
+  <w:SpellingState>Clean</w:SpellingState>
+  <w:GrammarState>Clean</w:GrammarState>
+  <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel>
+ </w:WordDocument>
+</xml><![endif]-->
+<style>
+<!--
+ /* Style Definitions */
+ p.MsoNormal, li.MsoNormal, div.MsoNormal
+	{mso-style-parent:"";
+	margin:0cm;
+	margin-bottom:.0001pt;
+	mso-pagination:widow-orphan;
+	font-size:12.0pt;
+	font-family:"Times New Roman";
+	mso-fareast-font-family:"Times New Roman";}
+h1
+	{mso-style-next:Normal;
+	margin-top:12.0pt;
+	margin-right:0cm;
+	margin-bottom:3.0pt;
+	margin-left:0cm;
+	mso-pagination:widow-orphan;
+	page-break-after:avoid;
+	mso-outline-level:1;
+	font-size:16.0pt;
+	font-family:Arial;
+	mso-font-kerning:16.0pt;}
+h2
+	{mso-style-next:Normal;
+	margin-top:12.0pt;
+	margin-right:0cm;
+	margin-bottom:3.0pt;
+	margin-left:0cm;
+	mso-pagination:widow-orphan;
+	page-break-after:avoid;
+	mso-outline-level:2;
+	font-size:14.0pt;
+	font-family:Arial;
+	font-style:italic;}
+a:link, span.MsoHyperlink
+	{color:blue;
+	text-decoration:underline;
+	text-underline:single;}
+a:visited, span.MsoHyperlinkFollowed
+	{color:#606420;
+	text-decoration:underline;
+	text-underline:single;}
+span.SpellE
+	{mso-style-name:"";
+	mso-spl-e:yes;}
+span.GramE
+	{mso-style-name:"";
+	mso-gram-e:yes;}
+@page Section1
+	{size:612.0pt 792.0pt;
+	margin:72.0pt 90.0pt 72.0pt 90.0pt;
+	mso-header-margin:35.4pt;
+	mso-footer-margin:35.4pt;
+	mso-paper-source:0;}
+div.Section1
+	{page:Section1;}
+-->
+</style>
+<!--[if gte mso 10]>
+<style>
+ /* Style Definitions */
+ table.MsoNormalTable
+	{mso-style-name:"Table Normal";
+	mso-tstyle-rowband-size:0;
+	mso-tstyle-colband-size:0;
+	mso-style-noshow:yes;
+	mso-style-parent:"";
+	mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
+	mso-para-margin:0cm;
+	mso-para-margin-bottom:.0001pt;
+	mso-pagination:widow-orphan;
+	font-size:10.0pt;
+	font-family:"Times New Roman";}
+</style>
+<![endif]--><!--[if gte mso 9]><xml>
+ <o:shapedefaults v:ext="edit" spidmax="3074"/>
+</xml><![endif]--><!--[if gte mso 9]><xml>
+ <o:shapelayout v:ext="edit">
+  <o:idmap v:ext="edit" data="1"/>
+ </o:shapelayout></xml><![endif]-->
+</head>
+
+<body lang=EN-GB link=blue vlink="#606420" style='tab-interval:36.0pt'>
+
+<div class=Section1>
+
+<h1 align=center style='text-align:center'>Versioning of pre-built indexes</h1>
+
+<p class=MsoNormal>&nbsp;</p>
+
+<p class=MsoNormal style='text-align:justify'>In CDT 4.0.1 support for
+versioning of pre-built indexes was added. This means that if you release
+pre-built indexes for the same content (for example, the same SDK version), but
+they were built with different versions of CDT, then a suitable version will
+now be used automatically. The previous behaviour assumed only one format
+version of any particular content would be provided via the <span class=SpellE>CIndex</span>
+extension point.</p>
+
+<p class=MsoNormal style='text-align:justify'>&nbsp;</p>
+
+<p class=MsoNormal style='text-align:justify'>It is important to distinguish
+between two versions: the content version and the index format version. A
+content version refers to the version of the source code being indexed
+independent of how it is represented in the index e.g. SDK v1.0 and SDK v1.2.
+The index format version is the version of the internal representation of the
+index. This document is about coping with the latter.</p>
+
+<p class=MsoNormal style='text-align:justify'>&nbsp;</p>
+
+<p class=MsoNormal style='text-align:justify'>Our versioning policy for index
+formats is that they should be compatible within major (yearly) release
+versions. That is if you build an index using CDT 4.0.X it should work with CDT
+4.0.Y. This policy should mean that ISVs do not need to worry about index
+format versioning, but this page describes how to handle it should it be
+necessary (for example <span class=SpellE>bugzilla</span> 189811).Each
+pre-built index carries a string ID which identifies it uniquely within a
+logical index - i.e. it identifies the content (<span class=SpellE>e.g</span> <span
+class=SpellE>MySDK</span> v1.2). When multiple pre-built indexes are provided
+with the same ID, the particular one for use is disambiguated automatically by
+CDT which chooses the most recent compatible version.</p>
+
+<h2><span style='font-style:normal;mso-bidi-font-style:italic'>Compatibility
+Table<o:p></o:p></span></h2>
+
+<p class=MsoNormal>&nbsp;</p>
+
+<p class=MsoNormal style='text-align:justify'>This table shows the
+compatibility of pre-built indexes built with one version of CDT and used with
+another. “Built With” is the vertical axis.</p>
+
+<p class=MsoNormal>&nbsp;</p>
+
+<table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 width=516
+ style='width:387.0pt;margin-left:23.4pt;border-collapse:collapse;mso-padding-alt:
+ 0cm 0cm 0cm 0cm'>
+ <tr style='mso-yfti-irow:0'>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal><b><span style='font-size:8.0pt'>Built With \ Use With</span></b></p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>CDT 4.0</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>CDT 4.0.1</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>CDT Next**</p>
+  </td>
+  <td width=44 valign=top style='width:32.8pt;border:none;border-bottom:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal><b>&nbsp;</b></p>
+  </td>
+ </tr>
+ <tr style='mso-yfti-irow:1'>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>CDT 4.0</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>Yes*</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>Yes*</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>No</p>
+  </td>
+  <td width=44 valign=top style='width:32.8pt;border:none;border-bottom:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+ </tr>
+ <tr style='mso-yfti-irow:2'>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>CDT 4.0.1</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>Yes*</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>Yes</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>No</p>
+  </td>
+  <td width=44 valign=top style='width:32.8pt;border:none;border-bottom:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+ </tr>
+ <tr style='mso-yfti-irow:3'>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>CDT Next**</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>No</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>No</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border-top:none;border-left:
+  none;border-bottom:solid white 2.25pt;border-right:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>Yes</p>
+  </td>
+  <td width=44 valign=top style='width:32.8pt;border:none;border-bottom:solid white 2.25pt;
+  background:#F2F2F2;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+ </tr>
+ <tr style='mso-yfti-irow:4;mso-yfti-lastrow:yes'>
+  <td width=118 valign=top style='width:88.55pt;border:none;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border:none;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border:none;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+  <td width=118 valign=top style='width:88.55pt;border:none;border-right:solid white 2.25pt;
+  background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+  <td width=44 valign=top style='width:32.8pt;background:#CCCCCC;padding:0cm 5.4pt 0cm 5.4pt'>
+  <p class=MsoNormal>&nbsp;</p>
+  </td>
+ </tr>
+</table>
+
+<p class=MsoNormal>&nbsp;</p>
+
+<p class=MsoNormal style='text-align:justify'>Note that even though in the PDOM
+format has its own internal versioning scheme, consumers of official CDT
+releases need only be aware of compatibility constraints between these
+releases.</p>
+
+<p class=MsoNormal>&nbsp;</p>
+
+<p class=MsoNormal><span style='font-size:8.0pt'>* <span class=GramE>with</span>
+performance issues in very large projects. See <a
+href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=189811">https://bugs.eclipse.org/bugs/show_bug.cgi?id=189811</a></span></p>
+
+<p class=MsoNormal><span class=GramE><span style='font-size:8.0pt'>** represents
+the next major release of CDT.</span></span><span style='font-size:8.0pt'> It
+is assumed significant changes to the PDOM database will occur.<o:p></o:p></span></p>
+
+<p class=MsoNormal><span style='font-size:8.0pt'><o:p>&nbsp;</o:p></span></p>
+
+<h2><span style='font-style:normal;mso-bidi-font-style:italic'>Example scenario<o:p></o:p></span></h2>
+
+<p class=MsoNormal><o:p>&nbsp;</o:p></p>
+
+<span style='font-size:12.0pt;font-family:"Times New Roman";mso-fareast-font-family:
+"Times New Roman";mso-ansi-language:EN-GB;mso-fareast-language:EN-GB;
+mso-bidi-language:AR-SA'><br clear=all style='page-break-before:always'>
+</span>
+
+<p class=MsoNormal align=center style='text-align:center'>&nbsp;</p>
+
+<p class=MsoNormal align=center style='text-align:center'><img border=0
+width=421 height=653 id="_x0000_i1025"
+src="prebuiltVersioning_files/image001.jpg"></p>
+
+<p class=MsoNormal align=center style='text-align:center'>&nbsp;</p>
+
+<p class=MsoNormal style='text-align:justify'>The figure above shows an example
+scenario where pre-built indexes are contributed by multiple <span class=GramE>plug-ins</span>.
+The same content is contributed in multiple index format versions. The versions
+selected for use by each version of CDT are highlighted in <span class=SpellE>gray</span>.</p>
+
+<p class=MsoNormal style='text-align:justify'><o:p>&nbsp;</o:p></p>
+
+<p class=MsoNormal style='text-align:justify'><o:p>&nbsp;</o:p></p>
+
+<p class=MsoNormal style='text-align:justify'><o:p>&nbsp;</o:p></p>
+
+<p class=MsoNormal><span style='font-size:10.0pt'>Versioning <span
+class=SpellE>Bugzilla</span>: <a
+href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=196338">https://bugs.eclipse.org/bugs/show_bug.cgi?id=196338</a></span></p>
+
+<p class=MsoNormal style='text-align:justify'><o:p>&nbsp;</o:p></p>
+
+</div>
+
+</body>
+
+</html>
diff --git a/doc/org.eclipse.cdt.doc.isv/guide/dom/index/prebuiltVersioning_files/image001.jpg b/doc/org.eclipse.cdt.doc.isv/guide/dom/index/prebuiltVersioning_files/image001.jpg
new file mode 100644
index 00000000000..0acc405f981
Binary files /dev/null and b/doc/org.eclipse.cdt.doc.isv/guide/dom/index/prebuiltVersioning_files/image001.jpg differ
diff --git a/doc/org.eclipse.cdt.doc.isv/topics_Guide.xml b/doc/org.eclipse.cdt.doc.isv/topics_Guide.xml
index c81a1aaac09..ae30603660c 100644
--- a/doc/org.eclipse.cdt.doc.isv/topics_Guide.xml
+++ b/doc/org.eclipse.cdt.doc.isv/topics_Guide.xml
@@ -6,6 +6,7 @@
 <toc label="Guide">
 	<topic label="CDT DOM" href="guide/dom/index.html">
 		<topic label="Prebuilt Indexes in CDT 4.0" href="guide/dom/index/prebuiltIndexes.html"/>
+		<topic label="Versioning of Prebuilt Indexes" href="guide/dom/index/prebuiltVersioning.html"/>
 	</topic>
 	<topic label="Managed Build System Extensibility Document" href="guide/mbs/extensibilityGuide/Managed_Build_Extensibility.html"/>
 	<topic label="Project Template Engine" href="guide/projectTemplateEngine/index.html"/>