Fix docs. (ethereum#916)

docs/control-structures.rst

@@ -87,7 +87,10 @@ parentheses at the end perform the actual call.
 Named Calls and Anonymous Function Parameters
 ---------------------------------------------
 
-Function call arguments can also be given by name, in any order.
+Function call arguments can also be given by name, in any order,
+if they are enclosed in ``{ }`` as can be seen in the following
+example. The argument list has to coincide by name with the list of
+parameters from the function declaration, but can be in arbitrary order.
 
 ::
 
@@ -99,9 +102,12 @@ Function call arguments can also be given by name, in any order.
             f({value: 2, key: 3});
         }
     }
-Note that when calling the function, the argument list must match by name every parameter from the function declaration - though in an arbitrary order.
 
-Also, the names of unused parameters (especially return parameters) can be omitted.
+Omitted Function Parameter Names
+--------------------------------
+
+The names of unused parameters (especially return parameters) can be omitted.
+Those names will still be present on the stack, but they are inaccessible.
 
 ::