Index: /trunk/src/VBox/Main/idl/VirtualBox.xidl
===================================================================
--- /trunk/src/VBox/Main/idl/VirtualBox.xidl	(revision 23935)
+++ /trunk/src/VBox/Main/idl/VirtualBox.xidl	(revision 23936)
@@ -4803,5 +4803,6 @@
 
         The specified device slot can have a medium mounted, which will be
-        unmounted first. Specifying a NULL medium does just an unmount.
+        unmounted first. Specifying a zero UUID (or an empty string) for
+        @a medium does just an unmount.
 
         See <link to="IMedium"/> for more detailed information about
@@ -4831,6 +4832,7 @@
         <desc>Device slot in the given port to attach the medium to.</desc>
       </param>
-      <param name="id" type="uuid" mod="string" dir="in">
-        <desc>UUID of the medium to attach.</desc>
+      <param name="medium" type="uuid" mod="string" dir="in">
+        <desc>UUID of the medium to attach. A zero UUID means unmount the
+          currently mounted medium.</desc>
       </param>
     </method>