diff --git a/docs/caching-proxies.rst b/docs/caching-proxies.rst
index adb3780..f5955fc 100644
--- a/docs/caching-proxies.rst
+++ b/docs/caching-proxies.rst
@@ -22,7 +22,13 @@ returned to a user, because the cache has not been updated since the item
 was modified. There are three general strategies for dealing with this:
 
 * Since resources are cached in the proxy based on their URL, you can
-  "invalidate" the cached copy by changing an item's URL when it is updated. This approach has the benefit of also being able to
+  "invalidate" the cached copy by changing an item's URL when it is updated.
+  This is the approach taken by Plone's ResourceRegistries:
+  in production mode, the links that are inserted
+  into Plone's content pages for resource managed by ResourceRegistries
+  contain a time-based token, which changes when the ResourceRegistries
+  are updated, more specifically: when the resource bundles are combined.
+  This approach has the benefit of also being able to
   "invalidate" content stored in a user's browser cache.
 
 * All caching proxies support setting timeouts. This means that content may
@@ -85,7 +91,8 @@ The default purge paths include:
   ``Image`` types.
 
 Files and images created (or customised) in the ZMI are purged automatically
-when modified. To purge Plone content when modified
+when modified. Files managed through the ResourceRegistries do not need
+purging, since they have "stable" URLs. To purge Plone content when modified
 (or removed), you must select the content types in the control panel. By
 default, only the ``File`` and ``Image`` types are purged.
 
diff --git a/docs/etags.rst b/docs/etags.rst
index 9b842c3..3cdc796 100644
--- a/docs/etags.rst
+++ b/docs/etags.rst
@@ -42,6 +42,11 @@ The ETag names tokens supported by default are:
 * skin
     The name of the current skin (theme)
 
+* resourceRegistries
+    A timestamp indicating the last-modified timestamp for the
+    Resource Registries. This is useful for avoiding requests for expired
+    resources from cached pages.
+
 It is possible to provide additional tokens by registering an ``IETagValue``
 adapter. This should be a named adapter on the published object (typically a
 view, file resource or Zope page template object) and request, with a unique
diff --git a/plone/app/caching/profiles/with-caching-proxy-splitviews/registry.xml b/plone/app/caching/profiles/with-caching-proxy-splitviews/registry.xml
index 3d32eb3..22943d7 100644
--- a/plone/app/caching/profiles/with-caching-proxy-splitviews/registry.xml
+++ b/plone/app/caching/profiles/with-caching-proxy-splitviews/registry.xml
@@ -21,6 +21,7 @@
           <element>userLanguage</element>
           <element>skin</element>
           <element>locked</element>
+          <element>resourceRegistries</element>
       </value>
   </record>
   <record name="plone.app.caching.moderateCaching.plone.content.itemView.ramCache">
@@ -48,6 +49,7 @@
           <element>skin</element>
           <element>locked</element>
           <element>copy</element>
+          <element>resourceRegistries</element>
       </value>
   </record>
   <record name="plone.app.caching.moderateCaching.plone.content.folderView.ramCache">
@@ -117,4 +119,4 @@
   </record>
 
 
-</registry>
+</registry>
\ No newline at end of file
diff --git a/plone/app/caching/profiles/with-caching-proxy/registry.xml b/plone/app/caching/profiles/with-caching-proxy/registry.xml
index 56c2264..0d30b49 100644
--- a/plone/app/caching/profiles/with-caching-proxy/registry.xml
+++ b/plone/app/caching/profiles/with-caching-proxy/registry.xml
@@ -21,6 +21,7 @@
           <element>userLanguage</element>
           <element>skin</element>
           <element>locked</element>
+          <element>resourceRegistries</element>
       </value>
   </record>
   <record name="plone.app.caching.weakCaching.plone.content.itemView.ramCache">
@@ -39,6 +40,7 @@
           <element>skin</element>
           <element>locked</element>
           <element>copy</element>
+          <element>resourceRegistries</element>
       </value>
   </record>
   <record name="plone.app.caching.weakCaching.plone.content.folderView.ramCache">
diff --git a/plone/app/caching/profiles/without-caching-proxy/registry.xml b/plone/app/caching/profiles/without-caching-proxy/registry.xml
index 3569909..bdbe9b4 100644
--- a/plone/app/caching/profiles/without-caching-proxy/registry.xml
+++ b/plone/app/caching/profiles/without-caching-proxy/registry.xml
@@ -21,6 +21,7 @@
           <element>userLanguage</element>
           <element>skin</element>
           <element>locked</element>
+          <element>resourceRegistries</element>
       </value>
   </record>
   <record name="plone.app.caching.weakCaching.plone.content.itemView.ramCache">
@@ -39,6 +40,7 @@
           <element>skin</element>
           <element>locked</element>
           <element>copy</element>
+          <element>resourceRegistries</element>
       </value>
   </record>
   <record name="plone.app.caching.weakCaching.plone.content.folderView.ramCache">
@@ -92,4 +94,4 @@
   </record>
 
 
-</registry>
+</registry>
\ No newline at end of file
diff --git a/plone/app/caching/tests/test_profile_with_caching_proxy.py b/plone/app/caching/tests/test_profile_with_caching_proxy.py
index 320371d..b3897eb 100644
--- a/plone/app/caching/tests/test_profile_with_caching_proxy.py
+++ b/plone/app/caching/tests/test_profile_with_caching_proxy.py
@@ -147,7 +147,7 @@ def test_composite_viewsxx(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        self.assertEqual('"|test_user_1_|%d|en|%s|0' % (catalog.getCounter(
+        self.assertEqual('"|test_user_1_|%d|en|%s|0|0' % (catalog.getCounter(
         ), skins_tool.default_skin), _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
@@ -162,7 +162,7 @@ def test_composite_viewsxx(self):
                          browser.headers['X-Cache-Operation'])
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        self.assertEqual('"|test_user_1_|%d|en|%s|0' % (catalog.getCounter(
+        self.assertEqual('"|test_user_1_|%d|en|%s|0|1' % (catalog.getCounter(
         ), skins_tool.default_skin), _normalize_etag(browser.headers['ETag']))
 
         # Request the authenticated page
@@ -181,7 +181,7 @@ def test_composite_viewsxx(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        self.assertEqual('"|test_user_1_|%d|en|%s' % (catalog.getCounter(
+        self.assertEqual('"|test_user_1_|%d|en|%s|0' % (catalog.getCounter(
         ), skins_tool.default_skin), _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
@@ -227,7 +227,7 @@ def test_composite_viewsxx(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        self.assertEqual('"||%d|en|%s|0' % (catalog.getCounter(
+        self.assertEqual('"||%d|en|%s|0|0' % (catalog.getCounter(
         ), skins_tool.default_skin), _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
@@ -244,7 +244,7 @@ def test_composite_viewsxx(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        self.assertEqual('"||%d|en|%s' % (catalog.getCounter(
+        self.assertEqual('"||%d|en|%s|0' % (catalog.getCounter(
         ), skins_tool.default_skin), _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
@@ -264,7 +264,7 @@ def test_composite_viewsxx(self):
         self.assertIn(testText, browser.contents)
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        self.assertEqual('"||%d|en|%s' % (catalog.getCounter(
+        self.assertEqual('"||%d|en|%s|0' % (catalog.getCounter(
         ), skins_tool.default_skin), _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
diff --git a/plone/app/caching/tests/test_profile_without_caching_proxy.py b/plone/app/caching/tests/test_profile_without_caching_proxy.py
index d19db4e..0692758 100644
--- a/plone/app/caching/tests/test_profile_without_caching_proxy.py
+++ b/plone/app/caching/tests/test_profile_without_caching_proxy.py
@@ -135,7 +135,7 @@ def test_composite_views(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        tag = '"|test_user_1_|{0}|en|{1}|0'.format(
+        tag = '"|test_user_1_|{0}|en|{1}|0|0'.format(
             catalog.getCounter(),
             default_skin,
         )
@@ -153,7 +153,7 @@ def test_composite_views(self):
                          browser.headers['X-Cache-Operation'])
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        tag = '"|test_user_1_|{0}|en|{1}|0'.format(
+        tag = '"|test_user_1_|{0}|en|{1}|0|1'.format(
             catalog.getCounter(),
             default_skin,
         )
@@ -175,7 +175,7 @@ def test_composite_views(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        tag = '"|test_user_1_|{0}|en|{1}'.format(
+        tag = '"|test_user_1_|{0}|en|{1}|0'.format(
             catalog.getCounter(),
             default_skin,
         )
@@ -223,7 +223,7 @@ def test_composite_views(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        tag = '"||{0}|en|{1}|0'.format(catalog.getCounter(), default_skin)
+        tag = '"||{0}|en|{1}|0|0'.format(catalog.getCounter(), default_skin)
         self.assertEqual(tag, _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
@@ -240,7 +240,7 @@ def test_composite_views(self):
         # This should use cacheInBrowser
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        tag = '"||{0}|en|{1}'.format(catalog.getCounter(), default_skin)
+        tag = '"||{0}|en|{1}|0'.format(catalog.getCounter(), default_skin)
         self.assertEqual(tag, _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))
@@ -260,7 +260,7 @@ def test_composite_views(self):
         self.assertIn(testText, browser.contents)
         self.assertEqual('max-age=0, must-revalidate, private',
                          browser.headers['Cache-Control'])
-        tag = '"||{0}|en|{1}'.format(catalog.getCounter(), default_skin)
+        tag = '"||{0}|en|{1}|0'.format(catalog.getCounter(), default_skin)
         self.assertEqual(tag, _normalize_etag(browser.headers['ETag']))
         self.assertGreater(now, dateutil.parser.parse(
             browser.headers['Expires']))