diff --git a/prism/NOTES b/prism/NOTES
index ff80f3b2..b6228892 100644
--- a/prism/NOTES
+++ b/prism/NOTES
@@ -22,6 +22,8 @@ TODO (before public release)
 ----------------------------
 
 Filters, property semantics, etc.
+* {}-filters should be "first", not "range" for 1-state filters
+  (need to move invisible filter creation into StateModelChecker I think)
 * Integer-valued props displayed as doubles when printed as vector
 * Intervals (e.g. for multiple initial states) plotted in graphs