Index: doc/proposals/virtual.txt
===================================================================
--- doc/proposals/virtual.txt	(revision da81e1d010ac441c7d9fbead80f54b6be912fe99)
+++ doc/proposals/virtual.txt	(revision ba5131d8cb1502b70831a686b5789f6d314df23d)
@@ -104,5 +104,7 @@
 One of the limitations of this design is that it does not support double dispatching, which
 concretely means traits cannot have routines with more than one virtual parameter. This design
-would have many ambiguities if it did support multiple virtual parameter.
+would have many ambiguities if it did support multiple virtual parameter. A futher limitation is 
+that traits over more than one type cannot have vtables meaningfully defined for them, as the 
+particular vtable to use would be a function of the other type(s) the trait is defined over.
 
 It is worth noting that the function pointers in these vtables are bound at object construction, rather than