diff --git a/schema-0.4/schema-0.4.jsd b/schema-0.4/schema-0.4.jsd
index da64ab5..8462a9c 100644
--- a/schema-0.4/schema-0.4.jsd
+++ b/schema-0.4/schema-0.4.jsd
@@ -24,7 +24,9 @@
     "properties": {
       "doc": {
         "jx:type": "string",
-        "doc": "Defines text comments. Optional."
+        "doc": "Defines text comments. Optional.",
+        "@nullable": false,
+        "@use": "optional"
       }
     }
   },
diff --git a/schema-0.4/schema-0.4.jsdx b/schema-0.4/schema-0.4.jsdx
index b268e67..8b5cfb2 100644
--- a/schema-0.4/schema-0.4.jsdx
+++ b/schema-0.4/schema-0.4.jsdx
@@ -26,7 +26,7 @@
   <string name="nonEmptyString" pattern="\S|\S.*\S"/>
 
   <object name="documented" abstract="true">
-    <property name="doc" xsi:type="string" doc="Defines text comments. Optional."/>
+    <property name="doc" xsi:type="string" use="optional" nullable="false" doc="Defines text comments. Optional."/>
   </object>
 
   <object name="member" abstract="true" extends="documented"/>
diff --git a/schema-0.5/schema-0.5.jsd b/schema-0.5/schema-0.5.jsd
index 1f6b81d..bb84e11 100644
--- a/schema-0.5/schema-0.5.jsd
+++ b/schema-0.5/schema-0.5.jsd
@@ -40,7 +40,9 @@
     "@properties": {
       "@doc": {
         "@": "string",
-        "@doc": "Defines text comments. Optional."
+        "@doc": "Defines text comments. Optional.",
+        "@nullable": false,
+        "@use": "optional"
       }
     }
   },
diff --git a/schema-0.5/schema-0.5.jsdx b/schema-0.5/schema-0.5.jsdx
index 5741583..fb7d11b 100644
--- a/schema-0.5/schema-0.5.jsdx
+++ b/schema-0.5/schema-0.5.jsdx
@@ -30,7 +30,7 @@
   <string name="schemaLocation" pattern="((\S|\S.*\S) (\S|\S.*\S))+"/>
 
   <object name="documented" abstract="true">
-    <property name="@doc" xsi:type="string" doc="Defines text comments. Optional."/>
+    <property name="@doc" xsi:type="string" use="optional" nullable="false" doc="Defines text comments. Optional."/>
   </object>
 
   <object name="member" abstract="true" extends="documented"/>