diff --git a/transforms01/adl2controllerclasses.xslt b/transforms01/adl2controllerclasses.xslt
index 2e9de19..beac2ae 100755
--- a/transforms01/adl2controllerclasses.xslt
+++ b/transforms01/adl2controllerclasses.xslt
@@ -9,8 +9,8 @@
     Transform ADL into (partial) controller classes
     
     $Author: sb $
-    $Revision: 1.22 $
-    $Date: 2008-04-18 09:27:29 $
+    $Revision: 1.23 $
+    $Date: 2008-05-08 17:26:44 $
   -->
 
   <!-- WARNING WARNING WARNING: Do NOT reformat this file! 
@@ -71,7 +71,7 @@
 //
 //  Controller for auto-generated forms for editing <xsl:value-of select="@name"/>s
 //  Automatically generated from application description using
-//  adl2controllerclasses.xslt version <xsl:value-of select="substring( '$Revision: 1.22 $', 10)"/>
+//  adl2controllerclasses.xslt version <xsl:value-of select="substring( '$Revision: 1.23 $', 10)"/>
 //
 //  This file is automatically generated; DO NOT EDIT IT.
 //
@@ -128,7 +128,7 @@ namespace <xsl:value-of select="$controllerns"/> {
 //
 //  Controller for auto-generated forms for editing <xsl:value-of select="@name"/>s
 //  Automatically generated from application description using
-//  adl2controllerclasses.xslt version <xsl:value-of select="substring( '$Revision: 1.22 $', 10)"/>
+//  adl2controllerclasses.xslt version <xsl:value-of select="substring( '$Revision: 1.23 $', 10)"/>
 //
 //  This file is automatically generated; DO NOT EDIT IT.
 //
@@ -186,18 +186,27 @@ namespace <xsl:value-of select="$controllerns"/> {
         // update permissions, seeing that we use an update operation to set the
         // field values and save the entity.
         Boolean isnewborn = false;
+		
+        <xsl:call-template name="fetch-instance">
+			<xsl:with-param name="entity" select="."/>
+			<xsl:with-param name="initialise-locals" select="'true'"/>
+        </xsl:call-template>
+
+        try {
+        <xsl:if test="adl:property[@distinct='system' or @distinct='all']">
+          /* declare a list of <xsl:value-of select="@name"/> to use in
+           * distinctness checks */
+          IList&lt;<xsl:value-of select="@name"/>&gt; matches = null;
+        </xsl:if>
 
         <xsl:apply-templates select="descendant::adl:property"/>
 
-        <xsl:call-template name="fetch-instance">
-          <xsl:with-param name="entity" select="."/>
-        </xsl:call-template>
-
-        if ( record == null) {
-          /* it seems to be new, create persistent object */
-          AssertUserCanCreate();
-          try {
-            record = new <xsl:value-of select="concat($entityns, '.', @name)"/>(<xsl:for-each select="adl:key/adl:property">
+          if ( record == null) {
+            /* it seems to be new, create persistent object */
+            AssertUserCanCreate();
+        
+            try {
+              record = new <xsl:value-of select="concat($entityns, '.', @name)"/>(<xsl:for-each select="adl:key/adl:property">
           <xsl:variable name="basetype">
             <xsl:call-template name="base-type">
               <xsl:with-param name="property" select="."/>
@@ -227,69 +236,72 @@ namespace <xsl:value-of select="$controllerns"/> {
             <xsl:otherwise>, </xsl:otherwise>
           </xsl:choose>
         </xsl:for-each>);
+            }
+            catch ( FormatException) {
+              /* failed to parse a number - not wholly unexpected, since it's most likely 
+               that an empty string was passed in */
+              record = new <xsl:value-of select="concat($entityns, '.', @name)"/>();
+            }
+            catch ( NullReferenceException) {
+              /* again, probably more normal than otherwise */
+              record = new <xsl:value-of select="concat($entityns, '.', @name)"/>();
+            }
+            messages.Add( "New <xsl:value-of select="@name"/> record created");
+              isnewborn = true;
           }
-          catch ( FormatException) {
-            /* failed to parse a number - not wholly unexpected, since it's most likely 
-            that an empty string was passed in */
-            record = new <xsl:value-of select="concat($entityns, '.', @name)"/>();
-          }
-          catch ( NullReferenceException) {
-            /* again, probably more normal than otherwise */
-            record = new <xsl:value-of select="concat($entityns, '.', @name)"/>();
-          }
-          messages.Add( "New <xsl:value-of select="@name"/> record created");
-          isnewborn = true;
-        }
 
-        if ( record != null) {
-          if ( ! isnewborn) {
-            // isnewborn cannot be true unless we've already checked user can create
-            // so no need to do it again here
-            AssertUserCanUpdate();
-          }
+          if ( record != null) {
+            /* a transaction to ensure our database operations are atomic */
+            ITransaction tx = null;
+
+            if ( ! isnewborn) {
+              // isnewborn cannot be true unless we've already checked user can create
+              // so no need to do it again here
+              AssertUserCanUpdate();
+            }
           
-          try {
-            /* actually update the record */
-            BindObjectInstance( record, ParamStore.Form, "instance");
+            try {
+              /* actually update the record */
+              BindObjectInstance( record, ParamStore.Form, "instance");
 
         <xsl:if test="descendant::adl:property[@type='message']">
-            /* there is at least one slot whose value is an internationalised message; 
-             * if these have yet to be initialised they must be handled specially */
-            Locale locale = GetBestLocaleForUser();
+              /* there is at least one slot whose value is an internationalised message; 
+               * if these have yet to be initialised they must be handled specially */
+              Locale locale = GetBestLocaleForUser();
           <xsl:for-each select="descendant::adl:property[@type='message']">
-            if ( ! String.IsNullOrEmpty( Form["<xsl:value-of select="concat( 'i18n.instance.', @name)"/>"])){
-              /* there's an uninitialised message for this slot */
-              Message mess = record.<xsl:value-of select="@name"/>;
-              if ( mess == null){
-                mess = new Message();
-              }
-              hibernator.Save( mess);
+              if ( ! String.IsNullOrEmpty( Form["<xsl:value-of select="concat( 'i18n.instance.', @name)"/>"])){
+                /* there's an uninitialised message for this slot */
+                Message mess = record.<xsl:value-of select="@name"/>;
+                if ( mess == null){
+                  mess = new Message();
+                }
+                hibernator.Save( mess);
 
-              Translation trans = mess.GetTranslationObject( locale, hibernator);
-              if ( trans == null) {
-                trans = new Translation( mess, locale);
+                Translation trans = mess.GetTranslationObject( locale, hibernator);
+                if ( trans == null) {
+                  trans = new Translation( mess, locale);
+                }
+                trans.MessageText = Form["<xsl:value-of select="concat( 'i18n.instance.', @name)"/>"];
+                record.<xsl:value-of select="@name"/> = mess;
+                hibernator.Save( trans);
               }
-              trans.MessageText = Form["<xsl:value-of select="concat( 'i18n.instance.', @name)"/>"];
-              record.<xsl:value-of select="@name"/> = mess;
-              hibernator.Save( trans);
-            }
           </xsl:for-each>
         </xsl:if>
 
         <xsl:for-each select="descendant::adl:property[@type='entity']">
-            /* for properties of type 'entity', it should not be necessary to do anything 
-             * special - BindObjectInstance /should/ do it all. Unfortunately it sometimes 
-             * doesn't, and I haven't yet characterised why not. */
+              /* for properties of type 'entity', it should not be necessary to do anything 
+               * special - BindObjectInstance /should/ do it all. Unfortunately it sometimes 
+               * doesn't, and I haven't yet characterised why not. */
               <xsl:variable name="entityname" select="@entity"/>
               <xsl:choose>
                 <xsl:when test="//adl:entity[@name=$entityname]">
-            if ( ! String.IsNullOrEmpty( Form["<xsl:value-of select="concat( 'instance.', @name)"/>"]))
-            {
-              record.<xsl:value-of select="@name"/> = <xsl:call-template name="fetch-property-instance">
+              if ( ! String.IsNullOrEmpty( Form["<xsl:value-of select="concat( 'instance.', @name)"/>"]))
+              {
+                record.<xsl:value-of select="@name"/> = <xsl:call-template name="fetch-property-instance">
                 <xsl:with-param name="property" select="."/>
                 <xsl:with-param name="valuename" select="concat( 'instance.', @name)"/>
               </xsl:call-template>;
-            }
+              }
                 </xsl:when>
                 <xsl:otherwise>
                   <xsl:message terminate="yes">
@@ -301,120 +313,132 @@ namespace <xsl:value-of select="$controllerns"/> {
             </xsl:for-each>
 
                 <xsl:for-each select="property[@type='link']">  
-            /* to update a link table which has no other data than the near and far keys, it is
-             * sufficient to smash the existing values and create new ones. It's also a lot easier! */
+              /* to update a link table which has no other data than the near and far keys, it is
+               * sufficient to smash the existing values and create new ones. It's also a lot easier! */
         
-            string[] <xsl:value-of select="concat(@name, 'Values')"/> = Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>");
+              string[] <xsl:value-of select="concat(@name, 'Values')"/> = Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>");
           
-            if ( <xsl:value-of select="concat(@name, 'Values')"/> != null)
-            {
-              /* update the linking table for my <xsl:value-of select="@name"/>; first smash the old values */
-              if ( <xsl:value-of select="concat( 'record.', @name)"/> != null)
+              if ( <xsl:value-of select="concat(@name, 'Values')"/> != null)
               {
-                <xsl:value-of select="concat( 'record.', @name)"/>.Clear();
-              }
-              else
-              {
-                <xsl:value-of select="concat( 'record.', @name)"/> = new HashedSet&lt;<xsl:value-of select="@entity"/>&gt;();
-              }
+                /* update the linking table for my <xsl:value-of select="@name"/>; first smash the old values */
+                if ( <xsl:value-of select="concat( 'record.', @name)"/> != null)
+                {
+                  <xsl:value-of select="concat( 'record.', @name)"/>.Clear();
+                }
+                else
+                {
+                  <xsl:value-of select="concat( 'record.', @name)"/> = new HashedSet&lt;<xsl:value-of select="@entity"/>&gt;();
+                }
             
-              /* then reinstate the values from the indexes passed */
-              foreach ( string index in <xsl:value-of select="concat(@name, 'Values')"/>)
-              {
+                /* then reinstate the values from the indexes passed */
+                foreach ( string index in <xsl:value-of select="concat(@name, 'Values')"/>)
+                {
                 <xsl:value-of select="concat( 'record.', @name)"/>.Add(
                   hibernator.CreateCriteria(typeof(<xsl:value-of select="@entity"/>))
                     .Add(Expression.Eq("<xsl:value-of select="@entity"/>Id", index))
                     .UniqueResult&lt;<xsl:value-of select="$entityns"/>.<xsl:value-of select="@entity"/>&gt;());
+                }
               }
-            }
             </xsl:for-each>
 
             <xsl:for-each select="descendant::adl:property[@type='list']">
-            /* with a list we cannot just smash the old values! Instead we need to check 
-             * each one and exclude it if no longer required */
-            if ( Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>") != null)
-            {
-              string[] <xsl:value-of select="concat(@name, 'Values')"/> = Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>");
-
-              /* updating <xsl:value-of select="@name"/> child records; first remove any not on the submitted list */
-              foreach ( <xsl:value-of select="@entity"/> item in record.<xsl:value-of select="@name"/>)
+              /* with a list we cannot just smash the old values! Instead we need to check 
+               * each one and exclude it if no longer required */
+              if ( Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>") != null)
               {
-                String itemId = item.KeyString;
-                bool found = false;
+                string[] <xsl:value-of select="concat(@name, 'Values')"/> = Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>");
 
+                /* updating <xsl:value-of select="@name"/> child records; first remove any not on the submitted list */
+                foreach ( <xsl:value-of select="@entity"/> item in record.<xsl:value-of select="@name"/>)
+                {
+                  String itemId = item.KeyString;
+                  bool found = false;
+
+                  foreach ( string index in <xsl:value-of select="concat(@name, 'Values')"/>)
+                  {
+                    <!-- TODO: this could definitely be made more efficient -->
+                    if ( index.Equals( itemId))
+                    {
+                      found = true;
+                      break;
+                    }
+                  }
+          
+                  if ( ! found)
+                  {
+                    record.<xsl:value-of select="@name"/>.Remove( item);
+                  }
+                } /* foreach ( string index... */
+
+                /* then add any on the included list which are not already members */
                 foreach ( string index in <xsl:value-of select="concat(@name, 'Values')"/>)
                 {
-                  <!-- TODO: this could definitely be made more efficient -->
-                  if ( index.Equals( itemId))
-                  {
-                    found = true;
-                  }
-                }
-          
-                if ( ! found)
-                {
-                  record.<xsl:value-of select="@name"/>.Remove( item);
-                }
-              }
-
-              /* then add any on the included list which are not already members */
-              foreach ( string index in <xsl:value-of select="concat(@name, 'Values')"/>)
-              {
                 <xsl:variable name="entityname" select="@entity"/>
-                <xsl:value-of select="@entity"/> item = 
-                  hibernator.CreateCriteria(typeof(<xsl:value-of select="@entity"/>))
-                    .Add(Expression.Eq("<xsl:value-of select="@entity"/>Id", index))
-                    .UniqueResult&lt;<xsl:value-of select="$entityns"/>.<xsl:value-of select="@entity"/>&gt;();
+                  <xsl:value-of select="@entity"/> item = 
+                    hibernator.CreateCriteria(typeof(<xsl:value-of select="@entity"/>))
+                      .Add(Expression.Eq("<xsl:value-of select="@entity"/>Id", index))
+                      .UniqueResult&lt;<xsl:value-of select="$entityns"/>.<xsl:value-of select="@entity"/>&gt;();
               
-                if ( ! record.<xsl:value-of select="@name"/>.Contains( item))
-                {
-                  record.<xsl:value-of select="@name"/>.Add( item);
-                }
-              }
-            }
+                  if ( ! record.<xsl:value-of select="@name"/>.Contains( item))
+                  {
+                    record.<xsl:value-of select="@name"/>.Add( item);
+                  }
+                } /* foreach ( string index... */
+              } /* if ( Form.GetValues( "<xsl:value-of select="concat( 'instance.', @name)"/>") != null) */
             </xsl:for-each>
 
-            /* write the record to the database, in order to guarantee we have a valid key */
-            hibernator.Save(record);
-            hibernator.Flush();
+              /* write the record to the database, in order to guarantee we have a valid key */
+              hibernator.Save(record);
+              hibernator.Flush();
+              tx.Commit();
         
-            messages.Add( "Record saved successfully");
-          }
-          catch ( DataSuitabilityException dse)
-          {
-            AddError( dse.Message);
-          }
-          catch ( ApplicationException axe)
-          {
-            AddError( axe.Message);
+              messages.Add( "Record saved successfully");
+            } /* try actually commit */
+            catch ( Exception any) {
+              tx.Rollback();
+              messages.Add( "Record not saved");
+              throw any;
+            }
+          } /* if ( record != null) */
+          else {
+            throw new ApplicationException( String.Format( "No record of type <xsl:value-of select="@name"/> with the key values supplied was found"));
           }
+        } /* try */
+        catch ( DataSuitabilityException dse)
+        {
+          AddError( dse);
+        }
+        catch ( ApplicationException axe)
+        {
+          AddError( axe.Message);
+        }
 
-          PropertyBag["messages"] = messages;
-          PropertyBag["instance"] = record;    
+        PropertyBag["messages"] = messages;
+        PropertyBag["instance"] = record;    
             <xsl:if test="$authentication-layer = 'Database'">   
-          PropertyBag["username"] = Session[ NHibernateHelper.USERTOKEN];
+        PropertyBag["username"] = Session[ NHibernateHelper.USERTOKEN];
             </xsl:if>
         
-          if ( ! AssertNoErrors())
-          {
-            /* the session may be polluted; create a new session */
-            NHibernateHelper.CloseSession();
-            hibernator = NHibernateHelper.GetCurrentSession(<xsl:if test="$authentication-layer = 'Database'">
-        Session[ NHibernateHelper.USERTOKEN],
-        Session[NHibernateHelper.PASSTOKEN]
-      </xsl:if>);
-          }
-
-            <xsl:call-template name="formmenus">
-              <xsl:with-param name="form" select="adl:form[position()=1]"/>
-            </xsl:call-template>
-          RenderViewWithFailover("<xsl:value-of select="concat( adl:form[position()=1]/@name, '.vm')"/>", 
-              "<xsl:value-of select="concat( adl:form[position()=1]/@name, '.auto.vm')"/>");
-        }
-        else
+        if ( HasNoErrors())
         {
-          throw new DataRequiredException( "Record not found");
-        }
+          /* the session may be polluted; create a new session */
+          NHibernateHelper.CloseSession();
+          hibernator = NHibernateHelper.GetCurrentSession(<xsl:if test="$authentication-layer = 'Database'">
+            Session[ NHibernateHelper.USERTOKEN],
+            Session[NHibernateHelper.PASSTOKEN]
+      </xsl:if>);
+
+		  <xsl:call-template name="fetch-instance">
+			  <xsl:with-param name="entity" select="."/>
+			  <xsl:with-param name="initialise-locals" select="'false'"/>
+		  </xsl:call-template>
+
+		}
+		  <xsl:call-template name="formmenus">
+            <xsl:with-param name="form" select="adl:form[position()=1]"/>
+          </xsl:call-template>
+        RenderViewWithFailover("<xsl:value-of select="concat( adl:form[position()=1]/@name, '.vm')"/>", 
+              "<xsl:value-of select="concat( adl:form[position()=1]/@name, '.auto.vm')"/>");
       }
       </xsl:if>
 
@@ -436,7 +460,8 @@ namespace <xsl:value-of select="$controllerns"/> {
         if ( "true".Equals( reallydelete))
         {
         <xsl:call-template name="fetch-instance">
-          <xsl:with-param name="entity" select="."/>
+			<xsl:with-param name="entity" select="."/>
+			<xsl:with-param name="initialise-locals" select="'true'"/>
         </xsl:call-template>
 
           if ( record != null)
@@ -486,7 +511,7 @@ namespace <xsl:value-of select="$controllerns"/> {
           NHibernateHelper.GetCurrentSession( <xsl:if test="$authentication-layer = 'Database'">Session[ NHibernateHelper.USERTOKEN], 
                                               Session[NHibernateHelper.PASSTOKEN]</xsl:if>);
         IList&lt;<xsl:value-of select="concat( $entityns, '.', @name)"/>&gt; instances = 
-          hibernator.CreateCriteria(typeof(<xsl:value-of select="concat($entityns, '.', @name)"/>))<xsl:for-each select="property[@distinct='user']">
+          hibernator.CreateCriteria(typeof(<xsl:value-of select="concat($entityns, '.', @name)"/>))<xsl:for-each select="adl:property[@distinct='user']">
             <xsl:value-of select="concat( '.AddOrder( new Order( &#34;', @name, '&#34;, true))')"/>
           </xsl:for-each>.List&lt;<xsl:value-of select="concat($entityns, '.', @name)"/>&gt;();
 
@@ -515,16 +540,41 @@ namespace <xsl:value-of select="$controllerns"/> {
       </xsl:choose>);
         }
 
+      <xsl:choose>
+        <xsl:when test="adl:property[@distinct='system']">
+          <xsl:call-template name="check-property-value-distinct">
+            <xsl:with-param name="property" select="."/>
+          </xsl:call-template>
+        </xsl:when>
+        <xsl:when test="adl:property[@distinct='all']">
+          <xsl:call-template name="check-property-value-distinct">
+            <xsl:with-param name="property" select="."/>
+          </xsl:call-template>
+        </xsl:when>
+      </xsl:choose>
     </xsl:template>
 
-    <!-- suppress properties otherwise -->
-    <xsl:template match="adl:property"/>
-        
-    <xsl:template match="adl:ifmissing">
-      "<xsl:value-of select="normalize-space(.)"/>"
-    </xsl:template>
+	<xsl:template match="adl:property[@distinct='system']">
+		<xsl:call-template name="check-property-value-distinct">
+			<xsl:with-param name="property" select="."/>
+		</xsl:call-template>
+	</xsl:template>
 
-    <xsl:template match="adl:form">
+	<xsl:template match="adl:property[@distinct='all']">
+		<xsl:call-template name="check-property-value-distinct">
+			<xsl:with-param name="property" select="."/>
+		</xsl:call-template>
+	</xsl:template>
+
+
+	<!-- suppress properties otherwise -->
+	<xsl:template match="adl:property"/>
+
+	<xsl:template match="adl:ifmissing">
+		"<xsl:value-of select="normalize-space(.)"/>"
+	</xsl:template>
+
+	<xsl:template match="adl:form">
       <!-- xsl:variable name="key">
         <xsl:call-template name="primary-key-name">
           <xsl:with-param name="entity" select="ancestor::adl:entity"/>
@@ -539,16 +589,14 @@ namespace <xsl:value-of select="$controllerns"/> {
       /// Handle the submission of the form named <xsl:value-of select="@name"/>
       /// &lt;/summary&gt;
       [AccessibleThrough(Verb.Post)]
-      public void <xsl:value-of select="concat( @name, 'SubmitHandler')"/>( )
-      {
-        string command = Form[ "command"];
+      public void <xsl:value-of select="concat( @name, 'SubmitHandler')"/>( ) {
+				string command = Form[ "command"];
 
-        if ( command == null)
-        {
-          throw new Exception( "No command?");
-        }
-        else
-      <xsl:for-each select=".//verb">
+				if ( command == null) {
+					throw new Exception( "No command?");
+				}
+				else
+				<xsl:for-each select=".//verb">
         if ( command.Equals( "<xsl:value-of select="@verb"/>"))
         {
           /* NOTE: You must write an implementation of this verb in a
@@ -565,6 +613,7 @@ namespace <xsl:value-of select="$controllerns"/> {
 
       <xsl:call-template name="fetch-instance">
         <xsl:with-param name="entity" select="ancestor::adl:entity"/>
+				<xsl:with-param name="initialise-locals" select="'true'"/>
       </xsl:call-template>
 
       <xsl:if test="$authentication-layer = 'Database'">   
@@ -716,7 +765,79 @@ namespace <xsl:value-of select="$controllerns"/> {
       /* <xsl:apply-templates/> */
     </xsl:template>
 
-  <!-- produce all menus for a given form: harder, but more efficient -->
+	<!-- for properties with @distinct='all' or @distinct='system', 
+		check that values are indeed distinct -->
+	<xsl:template name="check-property-value-distinct">
+		<xsl:param name="property"/>
+
+		<xsl:variable name="basetype">
+			<xsl:call-template name="base-type">
+				<xsl:with-param name="property" select="."/>
+			</xsl:call-template>
+		</xsl:variable>
+
+		<xsl:choose>
+			<xsl:when test="$property/ancestor::adl:key and not( $property/ancestor::adl:entity/adl:key[position()=2])">
+				<!-- if I'm the property of a key field and it is the only key field of my entity then
+					it is pointless trying to establish my distinctness -->
+			</xsl:when>
+			<xsl:when test="$property/@distinct = 'system' or $property/@distinct='all'">
+				/* <xsl:value-of select="$property/@name"/> should be distinct: check that it is */
+				matches =
+					hibernator.CreateCriteria(typeof(<xsl:value-of select="$property/ancestor::adl:entity/@name"/>))
+				<xsl:choose>
+					<xsl:when test="$basetype='string'">
+						.Add(Expression.Eq("<xsl:value-of select="$property/@name"/>", Form["<xsl:value-of select="concat('instance.', $property/@name)"/>"]))
+					</xsl:when>
+					<xsl:when test="$basetype='integer'">
+						.Add(Expression.Eq("<xsl:value-of select="$property/@name"/>", Int32.Parse( Form["<xsl:value-of select="concat('instance.', $property/@name)"/>"])))
+					</xsl:when>
+					<xsl:when test="$basetype='entity'">
+						.Add(Expression.Eq("<xsl:value-of select="$property/@name"/>",
+						<xsl:call-template name="fetch-property-instance">
+							<xsl:with-param name="property" select="."/>
+							<xsl:with-param name="valuename" select="adl:property[position()=1]/@name"/>
+						</xsl:call-template>))
+					</xsl:when>
+					<xsl:otherwise>
+						<xsl:message terminate="yes">
+							ADL: ERROR: don't yet know how to do distinctness checks for properties 
+							with base type <xsl:value-of select="$basetype"/>
+						</xsl:message>
+					</xsl:otherwise>
+				</xsl:choose>
+				<xsl:for-each select="$property/ancestor::adl:entity/adl:key">
+					.Add(Expression.Not(Expression.Eq("<xsl:value-of select="adl:property[position()=1]/@name"/>",<xsl:choose>
+						<xsl:when test="@type='entity'">
+							<xsl:call-template name="fetch-property-instance">
+								<!-- recurse -->
+								<xsl:with-param name="property" select="."/>
+								<xsl:with-param name="valuename" select="adl:property[position()=1]/@name"/>
+							</xsl:call-template>
+						</xsl:when>
+						<xsl:when test="@type='integer'">
+							Int32.Parse( Form["<xsl:value-of select="adl:property[position()=1]/@name"/>"])
+						</xsl:when>
+						<xsl:otherwise>
+							Form["<xsl:value-of select="adl:property[position()=1]/@name"/>"]
+						</xsl:otherwise>
+					</xsl:choose>)))
+				</xsl:for-each>
+					.List&lt;<xsl:value-of select="$property/ancestor::adl:entity/@name"/>&gt;();
+
+				if ( matches.Count > 0)
+				{
+					throw new
+						DataNotDistinctException(
+							String.Format("There is already a {0} with the {1} '{2}'",
+								"<xsl:value-of select="$property/ancestor::adl:entity/@name"/>", "<xsl:value-of select="$property/@name"/>", Form["<xsl:value-of select="concat('instance.', $property/@name)"/>"]));
+				}
+			</xsl:when>
+		</xsl:choose>
+	</xsl:template>
+
+
+	<!-- produce all menus for a given form: harder, but more efficient -->
   <xsl:template name="formmenus">
     <xsl:param name="form"/>
     <xsl:choose>
@@ -876,11 +997,15 @@ namespace <xsl:value-of select="$controllerns"/> {
   declared) called 'record' -->
   <xsl:template name="fetch-instance">
     <xsl:param name="entity"/>
-      <xsl:value-of select="concat($entityns, '.', $entity/@name)"/> record = null;  
-
+		<xsl:param name="initialise-locals" select="'false'"/>
         /* check whether values for all key slots have been passed in; if so, we're probably dealing with an
          * existing record */
+    <xsl:if test="$initialise-locals = 'true'">
+				/* the instance (record) of type <xsl:value-of select="$entity/@name"/> we're dealing with */
+				<xsl:value-of select="concat($entityns, '.', $entity/@name)"/> record = null;  
+				/* whether we have valid values for all the key fields */
         bool allkeys = true;
+		</xsl:if>
     <xsl:for-each select="$entity/adl:key/adl:property">
         if ( String.IsNullOrEmpty( Form["<xsl:value-of select="concat( 'instance.', @name)"/>"])) {
           allkeys = false;
@@ -893,7 +1018,6 @@ namespace <xsl:value-of select="$controllerns"/> {
 
         if ( allkeys){
           /* it's (probably) existing, retrieve it */
-
           record = hibernator.CreateCriteria(typeof(<xsl:value-of select="concat( $entityns, '.', $entity/@name)"/>))
     <xsl:for-each select="$entity/adl:key/adl:property">
       <xsl:variable name="basetype">