diff --git a/include/spirv/spir-v.xml b/include/spirv/spir-v.xml
index 6925ac1..112a828 100644
--- a/include/spirv/spir-v.xml
+++ b/include/spirv/spir-v.xml
@@ -23,10 +23,11 @@
     MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
     -->
     <!--
-    This file, spir-v.xml, is the SPIR-V Tool ID and Opcode registry. The
-    canonical version of the registry, together with related schema and
+    This file, spir-v.xml, is the SPIR-V Tool ID, opcode and enumerant registry.
+    The canonical version of the registry, together with related schema and
     documentation, can be found in the Khronos Registry at
-        http://www.khronos.org/registry/spir-v/
+    include/spirv/spir-v.xml in the master branch at
+    https://github.com/KhronosGroup/SPIRV-Headers
     -->
 
     <!-- SECTION: SPIR-V Tool ID Definitions  -->
@@ -77,28 +78,37 @@
     </ids>
 
     <!-- SECTION: SPIR-V Opcodes and Enumerants -->
-    <!-- Reserve new ranges for vendors in contiguous blocks of 64
-         preceding the "Future use" block below, and modify that block
-         accordingly.
 
-         Each vendor determines the use of values in their own ranges.
-         Vendors are not required to disclose those uses.  If the use of a
-         value is included in an extension that is adopted by a Khronos
-         extension or specification, then that value's use may be permanently
+    <!-- Vendors reserve new ranges of:
+           - opcode enumerants in the "opcode" list below, and
+           - non-opcode enumerants in the non-opcodes "enumerant" list below.
+         Both are reserved by contiguous blocks of 64, preceding the given
+         "Future use" blocks.
+
+         SPIR-V background:
+           - SPIR-V currently has well over 30 enums, including the opcode enum
+           - each enum has its own name space, allowing reuse of enumerants
+           - SPIR-V restricts opcode enumerants to 16 bits
+           - all other enums use 32-bit enumerants
+
+         Reservation rules:
+           - opcode reservations ("opcode") are only valid for opcodes
+           - non-opcode reservations ("enumerant") are not valid for opcodes
+           - reservations in the enumerant list are valid for all non-opcode enums
+           - it is simpler to use each non-opcode enumerant for only one purpose
+             but this is left to the discretion of the vendor
+           - all enumerants in a range should be used before allocating a new range
+             (several extensions can use enumerants from the same range)
+
+         Each vendor determines the use of enumerants in the ranges they
+         reserve. Vendors are not required to disclose those uses.  If the use
+         of an enumerant is included in an extension that is adopted by a Khronos
+         extension or specification, then that enumerant's use may be permanently
          fixed as if originally reserved in a Khronos range.
 
-         The SPIR Working Group strongly recommends:
-         - Each value is used for only one purpose.
-         - All values in a range should be used before allocating a new range.
-           For example, to avoid unused gaps in ranges, it is customary for
-           several extensions to use values from the same range.
-
-         The Id type "enum" is a synonym for "opcode".
-
-         Note that SPIR-V restricts opcode values to 16 bits.
          -->
 
-    <!-- Reserved opcode & enumerant blocks -->
+    <!-- Begin reservations of opcode enumerants -->
     <ids type="opcode" start="0" end="4095" vendor="Khronos" comment="Reserved opcodes, not available to vendors - see the SPIR-V Specification"/>
     <ids type="opcode" start="4096" end="4159" vendor="Mesa" comment="Contact TBD"/>
     <ids type="opcode" start="4160" end="4415" vendor="ARM"/>
@@ -113,15 +123,39 @@
     <ids type="opcode" start="5824" end="5951" vendor="Intel" comment="Contact michael.kinsner@intel.com"/>
     <ids type="opcode" start="5952" end="6015" vendor="Codeplay" comment="Contact victor@codeplay.com"/>
     <ids type="opcode" start="6016" end="6079" vendor="Khronos" comment="Contact @tobski"/>
-    <!-- Opcodes & enumerants reservable for future use. To get a block, allocate
+    <!-- Opcode enumerants to reserve for future use. To get a block, allocate
          multiples of 64 starting at the lowest available point in this
          block and add a corresponding <ids> tag immediately above. Make
          sure to fill in the vendor attribute, and preferably add a contact
          person/address in a comment attribute. -->
-
     <!-- Example new block: <ids type="opcode" start="XXXX" end="XXXX+64n-1" vendor="Add vendor" comment="Contact TBD"/> -->
+    <ids type="opcode" start="6080" end="65535" comment="Opcode range reservable for future use by vendors"/>
+    <!-- End reservations of opcodes -->
 
-    <ids type="opcode" start="6080" end="4294967295" comment="Opcode range reservable for future use by vendors"/>
+
+    <!-- Begin reservations of non-opcode enumerants -->
+    <ids type="enumerant" start="0" end="4095" vendor="Khronos" comment="Reserved enumerants, not available to vendors - see the SPIR-V Specification"/>
+    <ids type="enumerant" start="4096" end="4159" vendor="Mesa" comment="Contact TBD"/>
+    <ids type="enumerant" start="4160" end="4415" vendor="ARM"/>
+    <ids type="enumerant" start="4416" end="4479" vendor="Khronos" comment="SPV_ARB_shader_ballot - contact Neil Henning, neil.henning@amd.com"/>
+    <ids type="enumerant" start="4480" end="4991" vendor="Qualcomm" comment="Contact weifengz@qti.qualcomm.com"/>
+    <ids type="enumerant" start="4992" end="5247" vendor="AMD"/>
+    <ids type="enumerant" start="5248" end="5503" vendor="NVIDIA"/>
+    <ids type="enumerant" start="5504" end="5567" vendor="Imagination"/>
+    <ids type="enumerant" start="5568" end="5631" vendor="Intel" comment="Contact ben.ashbaugh@intel.com"/>
+    <ids type="enumerant" start="5632" end="5695" vendor="Google" comment="Contact dneto@google.com"/>
+    <ids type="enumerant" start="5696" end="5823" vendor="Intel" comment="Contact ben.ashbaugh@intel.com"/>
+    <ids type="enumerant" start="5824" end="5951" vendor="Intel" comment="Contact michael.kinsner@intel.com"/>
+    <ids type="enumerant" start="5952" end="6015" vendor="Codeplay" comment="Contact victor@codeplay.com"/>
+    <ids type="enumerant" start="6016" end="6079" vendor="Khronos" comment="Contact @tobski"/>
+    <!-- Enumerants to reserve for future use. To get a block, allocate
+         multiples of 64 starting at the lowest available point in this
+         block and add a corresponding <ids> tag immediately above. Make
+         sure to fill in the vendor attribute, and preferably add a contact
+         person/address in a comment attribute. -->
+    <!-- Example new block: <ids type="enumerant" start="XXXX" end="XXXX+64n-1" vendor="Add vendor" comment="Contact TBD"/> -->
+    <ids type="enumerant" start="6080" end="4294967295" comment="Enumerant range reservable for future use by vendors"/>
+    <!-- End reservations of enumerants -->
 
 
     <!-- SECTION: SPIR-V Loop Control Bit Reservations -->