diff --git a/xml/cl.xml b/xml/cl.xml
index 33f45ce8..561b74bf 100644
--- a/xml/cl.xml
+++ b/xml/cl.xml
@@ -882,7 +882,7 @@ server's OpenCL/api-docs repository.
         <enum bitpos="3"            name="CL_MEM_USE_HOST_PTR"/>
         <enum bitpos="4"            name="CL_MEM_ALLOC_HOST_PTR"/>
         <enum bitpos="5"            name="CL_MEM_COPY_HOST_PTR"/>
-            <unused start="6" comment="reserved"/>
+            <unused start="6" comment="reserved for cl_ext_immutable_memory_objects"/>
         <enum bitpos="7"            name="CL_MEM_HOST_WRITE_ONLY"/>
         <enum bitpos="8"            name="CL_MEM_HOST_READ_ONLY"/>
         <enum bitpos="9"            name="CL_MEM_HOST_NO_ACCESS"/>