diff --git a/TO-DO-List.md b/TO-DO-List.md
index b1b7c8f..1671a87 100644
--- a/TO-DO-List.md
+++ b/TO-DO-List.md
@@ -120,7 +120,8 @@ Contents:
      use the program bank register, which is easy.)  We probably can't
      track the value of B reliably, so we'll need some way to let the
      user specify what B should be, globally or by region.  Specify as an
-     absolute number or (for IIgs OMF) a segment reference.
+     absolute number or (for IIgs OMF) a segment reference.  The value reverts
+     to B=K on an address change.
    * Need to reduce the scope of symbols.  In a small program it's okay if
      everything is essentially global, but in a larger program that gets
      awkward.  We could break it down by bank, treating inter-bank symbols