XER handling bug

diff --git a/BUGS b/BUGS
index b921955..2d96f75 100644
--- a/BUGS
+++ b/BUGS
@@ -29,3 +29,6 @@
 5. Encoding or decoding of structures with combined length greater than 16MB
 is not tested.
 
+6. XER decoding does not support integer (INTEGER, ENUMERATED) values
+outside the signed long range.
+