diff --git a/build/tools/mk_sdk_repo_xml.sh b/build/tools/mk_sdk_repo_xml.sh
index b721200..ef2d51b 100755
--- a/build/tools/mk_sdk_repo_xml.sh
+++ b/build/tools/mk_sdk_repo_xml.sh
@@ -21,6 +21,7 @@
   cat <<EOFU
 Usage: $0 output.xml xml-schema [type [os zip[:dest]]*...]*
 where:
+- schema is one of 'repository' or 'addon'
 - type is one of ${TYPES// /, } (or their plural).
 - os   is one of  ${OSES// /, }.
 There can be more than one zip for the same type
@@ -40,15 +41,20 @@
 [[ -z "$OUT" ]] && error "Missing output.xml name."
 shift
 
+# Get the schema type. Must be either "repository" or "addon".
 SCHEMA="$1"
 [[ ! -f "$SCHEMA" ]] && error "Invalid XML schema name: $SCHEMA."
 shift
 
 # Get XML:NS for SDK from the schema
+# This will be something like "http://schemas.android.com/sdk/android/addon/3"
 XMLNS=$(sed -n '/xmlns:sdk="/s/.*"\(.*\)".*/\1/p' "$SCHEMA")
 [[ -z "$XMLNS" ]] && error "Failed to find xmlns:sdk in $SCHEMA."
 echo "## Using xmlns:sdk=$XMLNS"
 
+# Extract the schema version number from the XMLNS, e.g. it would extract "3"
+VERSION="${XMLNS##*/}"
+
 # Get the root element from the schema. This is the first element
 # which name starts with "sdk-" (e.g. sdk-repository, sdk-addon)
 ROOT=$(sed -n -e '/xsd:element.*name="sdk-/s/.*name="\(sdk-[^"]*\)".*/\1/p' "$SCHEMA")
@@ -80,37 +86,46 @@
 # Parse all archives.
 
 ATTRS=(
-  # for repository packages
-  Pkg.Revision                  revision
-  Pkg.Desc                      description
-  Platform.Version              version
-  AndroidVersion.ApiLevel       api-level
-  AndroidVersion.CodeName       codename
-  Platform.IncludedAbi          included-abi
-  Platform.MinToolsRev          min-tools-rev
-  Platform.MinPlatformToolsRev  min-platform-tools-rev
-  Extra.Vendor                  vendor
-  Extra.VendorId                vendor-id
-  Extra.VendorDisplay           vendor-display
-  Extra.NameDisplay             name-display
-  Extra.Path                    path
-  Extra.OldPaths                old-paths
-  Extra.MinApiLevel             min-api-level
-  Sample.MinApiLevel            min-api-level
-  SystemImage.Abi               abi
-  Layoutlib.Api                 layoutlib/api
-  Layoutlib.Revision            layoutlib/revision
-  # for addon packages
-  vendor                        vendor
-  vendor-id                     vendor-id
-  vendor-display                vendor-display
-  name                          name
-  name-id                       name-id
-  name-display                  name-display
-  description                   description
-  api                           api-level
-  version                       revision
-  revision                      revision
+  # Columns:
+  # --------------------------+------------------------+----------------------
+  # Name read from            | XML element written    | Min-XSD version
+  # source.properties         | to repository.xml      | where XML can be used
+  # --------------------------+------------------------+----------------------
+  # from source.properties for repository.xml packages
+  Pkg.Revision                  revision                 1
+  Pkg.Desc                      description              1
+  Platform.Version              version                  1
+  AndroidVersion.ApiLevel       api-level                1
+  AndroidVersion.CodeName       codename                 1
+  Platform.IncludedAbi          included-abi             5
+  Platform.MinToolsRev          min-tools-rev            1
+  Platform.MinPlatformToolsRev  min-platform-tools-rev   3
+  Sample.MinApiLevel            min-api-level            2
+  SystemImage.Abi               abi                      5
+  Layoutlib.Api                 layoutlib/api            4
+  Layoutlib.Revision            layoutlib/revision       4
+  # from source.properties for addon.xml packages
+  Extra.Vendor                  vendor                   1
+  Extra.VendorId                vendor-id                4
+  Extra.VendorDisplay           vendor-display           4
+  Extra.NameDisplay             name-display             4
+  Extra.Path                    path                     1
+  Extra.OldPaths                old-paths                3
+  Extra.MinApiLevel             min-api-level            2
+  # from addon manifest.ini for addon.xml packages
+  # (note that vendor/name are mapped to different XML elements based on the XSD version)
+  vendor-id                     vendor-id                4
+  vendor-display                vendor-display           4
+  vendor                        vendor-display           4
+  vendor                        vendor                   1
+  name-id                       name-id                  4
+  name-display                  name-display             4
+  name                          name-display             4
+  name                          name                     1
+  description                   description              1
+  api                           api-level                1
+  version                       revision                 1
+  revision                      revision                 1
 )
 
 function parse_attributes() {
@@ -118,15 +133,33 @@
   shift
   local RESULT=""
   local VALUE
+  local REV
+  local USED
 
+  # $1 here is the ATTRS list above.
   while [[ "$1" ]]; do
-    # Parse the property, if present. Any space is replaced by @
-    VALUE=$( grep "^$1=" "$PROPS" | cut -d = -f 2 | tr ' ' '@' | tr -d '\r' )
-    if [[ -n "$VALUE" ]]; then
-      RESULT="$RESULT $2 $VALUE"
+    # Check the version in which the attribute was introduced and
+    # ignore things which are too *new* for this schema. This lets
+    # us generate old schemas for backward compatibility purposes.
+    SRC=$1
+    DST=$2
+    REV=$3
+
+    if [[ $VERSION -ge $REV ]]; then
+      # Parse the property, if present. Any space is replaced by @
+      VALUE=$( grep "^$SRC=" "$PROPS" | cut -d = -f 2 | tr ' ' '@' | tr -d '\r' )
+      if [[ -n "$VALUE" ]]; then
+        # In case an XML element would be mapped multiple times,
+        # only use its first definition.
+        if [[ "${USED/$DST/}" == "$USED" ]]; then
+          USED="$USED $DST"
+          RESULT="$RESULT $DST $VALUE"
+        fi
+      fi
     fi
     shift
     shift
+    shift
   done
 
   echo "$RESULT"
@@ -136,20 +169,24 @@
   local OUT="$1"
   shift
   local KEY VALUE
-  local NODE LAST_NODE
+  local NODE LAST_NODE EXTRA_SPACE
 
   while [[ "$1" ]]; do
     KEY="$1"
     VALUE="${2//@/ }"
     NODE="${KEY%%/*}"
     KEY="${KEY##*/}"
-    [[ "$NODE" == "$KEY" ]] && NODE=""
-    if [[ "$NODE" != "$LAST_NODE" ]]; then
-        [[ "$LAST_NODE" ]] && echo "          </sdk:$LAST_NODE>" >> "$OUT"
-        LAST_NODE="$NODE"
-        [[ "$NODE"      ]] && echo "          <sdk:$NODE>" >> "$OUT"
+    if [[ "$NODE" == "$KEY" ]]; then
+      NODE=""
+      EXTRA_SPACE=""
     fi
-    echo "        <sdk:$KEY>$VALUE</sdk:$KEY>" >> "$OUT"
+    if [[ "$NODE" != "$LAST_NODE" ]]; then
+      EXTRA_SPACE="    "
+      [[ "$LAST_NODE" ]] && echo "          </sdk:$LAST_NODE>" >> "$OUT"
+      LAST_NODE="$NODE"
+      [[ "$NODE"      ]] && echo "          <sdk:$NODE>" >> "$OUT"
+    fi
+    echo "$EXTRA_SPACE        <sdk:$KEY>$VALUE</sdk:$KEY>" >> "$OUT"
     shift
     shift
   done
diff --git a/build/tools/sdk_repo.mk b/build/tools/sdk_repo.mk
index a0d93de..137a591 100644
--- a/build/tools/sdk_repo.mk
+++ b/build/tools/sdk_repo.mk
@@ -2,8 +2,10 @@
 
 .PHONY: sdk_repo
 
-SDK_REPO_DEPS :=
-SDK_REPO_XML_ARGS :=
+SDK_REPO_DEPS       :=
+SDK_REPO_XML_ARGS   :=
+SDK_EXTRAS_DEPS     :=
+SDK_EXTRAS_XML_ARGS :=
 
 # Define the name of a package zip file to generate
 # $1=OS (e.g. linux-x86, windows, etc)
@@ -100,6 +102,40 @@
 endef
 
 # -----------------------------------------------------------------
+# Rules for main host sdk
+
+ifneq ($(filter sdk win_sdk,$(MAKECMDGOALS)),)
+
+# Note that extras are now located in addon.xml, not in repository.xml,
+# so we capture all extras first.
+$(eval $(call mk-sdk-repo-pkg-3,$(HOST_OS),$(MAIN_SDK_ZIP),support,extras/android))
+SDK_EXTRAS_XML_ARGS := $(SDK_REPO_XML_ARGS)
+SDK_REPO_XML_ARGS   :=
+
+SDK_EXTRAS_DEPS += \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),support)
+
+
+$(eval $(call mk-sdk-repo-pkg-1,$(HOST_OS),$(MAIN_SDK_ZIP),tools))
+$(eval $(call mk-sdk-repo-pkg-1,$(HOST_OS),$(MAIN_SDK_ZIP),platform-tools))
+$(eval $(call mk-sdk-repo-pkg-1,$(HOST_OS),$(MAIN_SDK_ZIP),docs))
+$(eval $(call mk-sdk-repo-pkg-2,$(HOST_OS),$(MAIN_SDK_ZIP),platforms))
+$(eval $(call mk-sdk-repo-pkg-2,$(HOST_OS),$(MAIN_SDK_ZIP),samples))
+$(eval $(call mk-sdk-repo-pkg-3,$(HOST_OS),$(MAIN_SDK_ZIP),system-images,system-images/*))
+$(eval $(call mk-sdk-repo-sources,$(HOST_OS),$(MAIN_SDK_ZIP),sources))
+
+SDK_REPO_DEPS += \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),tools) \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),platform-tools) \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),docs) \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),platforms) \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),samples) \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),system-images) \
+		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),sources)
+
+endif
+
+# -----------------------------------------------------------------
 # Rules for win_sdk
 
 ifneq ($(WIN_SDK_ZIP),)
@@ -115,30 +151,19 @@
 endif
 
 # -----------------------------------------------------------------
-# Rules for main host sdk
+# Pickup the most recent xml schema for repository and add-on
 
-ifneq ($(filter sdk win_sdk,$(MAKECMDGOALS)),)
+SDK_REPO_XSD := \
+	$(lastword \
+	  $(wildcard \
+	    $(TOPDIR)sdk/sdkmanager/libs/sdklib/src/com/android/sdklib/repository/sdk-repository-*.xsd \
+	))
 
-$(eval $(call mk-sdk-repo-pkg-1,$(HOST_OS),$(MAIN_SDK_ZIP),tools))
-$(eval $(call mk-sdk-repo-pkg-1,$(HOST_OS),$(MAIN_SDK_ZIP),platform-tools))
-$(eval $(call mk-sdk-repo-pkg-1,$(HOST_OS),$(MAIN_SDK_ZIP),docs))
-$(eval $(call mk-sdk-repo-pkg-2,$(HOST_OS),$(MAIN_SDK_ZIP),platforms))
-$(eval $(call mk-sdk-repo-pkg-2,$(HOST_OS),$(MAIN_SDK_ZIP),samples))
-$(eval $(call mk-sdk-repo-pkg-3,$(HOST_OS),$(MAIN_SDK_ZIP),system-images,system-images/*))
-$(eval $(call mk-sdk-repo-pkg-3,$(HOST_OS),$(MAIN_SDK_ZIP),support,extras/android))
-$(eval $(call mk-sdk-repo-sources,$(HOST_OS),$(MAIN_SDK_ZIP),sources))
-
-SDK_REPO_DEPS += \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),tools) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),platform-tools) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),docs) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),platforms) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),samples) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),system-images) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),support) \
-		$(call sdk-repo-pkg-zip,$(HOST_OS),$(MAIN_SDK_ZIP),sources)
-
-endif
+SDK_ADDON_XSD := \
+	$(lastword \
+	  $(wildcard \
+	    $(TOPDIR)sdk/sdkmanager/libs/sdklib/src/com/android/sdklib/repository/sdk-addon-*.xsd \
+	))
 
 # -----------------------------------------------------------------
 # Rules for sdk addon
@@ -157,12 +182,6 @@
 
 SDK_ADDON_XML := $(dir $(ADDON_SDK_ZIP))/addon.xml
 
-SDK_ADDON_XSD := \
-	$(lastword \
-	  $(wildcard \
-	    $(TOPDIR)sdk/sdkmanager/libs/sdklib/src/com/android/sdklib/repository/sdk-addon-*.xsd \
-	))
-
 $(SDK_ADDON_XML): $(ADDON_SDK_ZIP)
 	$(hide) $(TOPDIR)development/build/tools/mk_sdk_repo_xml.sh \
 		$(SDK_ADDON_XML) $(SDK_ADDON_XSD) add-on $(HOST_OS) $(RENAMED_ADDON_ZIP)
@@ -174,17 +193,11 @@
 # -----------------------------------------------------------------
 # Rules for the SDK Repository XML
 
-SDK_REPO_XML := $(HOST_OUT)/sdk/repository.xml
+SDK_REPO_XML   := $(HOST_OUT)/sdk/repository.xml
+SDK_EXTRAS_XML := $(HOST_OUT)/sdk/repo-extras.xml
 
 ifneq ($(SDK_REPO_XML_ARGS),)
 
-# Pickup the most recent xml schema
-SDK_REPO_XSD := \
-	$(lastword \
-	  $(wildcard \
-	    $(TOPDIR)sdk/sdkmanager/libs/sdklib/src/com/android/sdklib/repository/sdk-repository-*.xsd \
-	))
-
 $(SDK_REPO_XML): $(SDK_REPO_DEPS)
 	$(hide) $(TOPDIR)development/build/tools/mk_sdk_repo_xml.sh \
 		$(SDK_REPO_XML) $(SDK_REPO_XSD) $(SDK_REPO_XML_ARGS)
@@ -197,8 +210,23 @@
 
 endif
 
+
+ifneq ($(SDK_EXTRAS_XML_ARGS),)
+
+$(SDK_EXTRAS_XML): $(SDK_EXTRAS_DEPS)
+	$(hide) $(TOPDIR)development/build/tools/mk_sdk_repo_xml.sh \
+		$(SDK_EXTRAS_XML) $(SDK_ADDON_XSD) $(SDK_EXTRAS_XML_ARGS)
+
+$(call dist-for-goals, sdk_repo, $(SDK_EXTRAS_XML))
+
+else
+
+$(SDK_EXTRAS_XML): ;
+
+endif
+
 # -----------------------------------------------------------------
 
-sdk_repo: $(SDK_REPO_DEPS) $(SDK_REPO_XML)
+sdk_repo: $(SDK_REPO_DEPS) $(SDK_REPO_XML) $(SDK_EXTRAS_XML)
 	@echo "Packing of SDK repository done"
 
diff --git a/sdk/support_source.properties b/sdk/support_source.properties
index 855afb3..b4e5eb6 100644
--- a/sdk/support_source.properties
+++ b/sdk/support_source.properties
@@ -1,5 +1,8 @@
 Pkg.UserSrc=false
 Pkg.Revision=8
 Extra.Vendor=android
+Extra.VendorId=android
+Extra.VendorDisplay=Android
+Extra.NameDisplay=Android Support Library
 Extra.Path=support
 Extra.OldPaths=compatibility