diff --git a/xml/api/crm_attribute-2.18.rng b/xml/api/crm_attribute-2.18.rng
index 9c16ce6351..6c040eaeff 100644
--- a/xml/api/crm_attribute-2.18.rng
+++ b/xml/api/crm_attribute-2.18.rng
@@ -1,31 +1,32 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <grammar xmlns="http://relaxng.org/ns/structure/1.0"
          datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
 
     <start>
         <ref name="element-crm_attribute"/>
     </start>
 
     <define name="element-crm_attribute">
         <choice>
-            <ref name="element-attribute" />
+            <zeroOrMore>
+                <ref name="element-attribute" />
+            </zeroOrMore>
         </choice>
     </define>
 
     <define name="element-attribute">
         <element name="attribute">
             <optional>
                 <attribute name="scope"> <text /> </attribute>
             </optional>
             <optional>
                 <attribute name="id"> <text /> </attribute>
             </optional>
+            <attribute name="name"> <text /> </attribute>
+            <attribute name="value"> <text /> </attribute>
             <optional>
-                <attribute name="name"> <text /> </attribute>
-            </optional>
-            <optional>
-                <attribute name="value"> <text /> </attribute>
+                <attribute name="host"> <text /> </attribute>
             </optional>
         </element>
     </define>
 </grammar>