diff --git a/NOTES b/NOTES
index b9c8b44..72bd5b1 100644
--- a/NOTES
+++ b/NOTES
@@ -489,6 +489,9 @@ U+2590 RIGHT HALF BLOCK
 ITU-T Recommendation T.100 is another standard that encodes 6-cell
 mosaic graphics.
 
+UK patent number 1343298 (filed 1971 by Mullard) describes the
+character rounding technique used by the SAA5050.
+
 FontForge's "Expand stroke" may be useful for converting single-line
 font into something useful.  A 50-unit circular pen generates Bedstead
 Plotter.  A 100×50-unit, 20° rectangular pen generates a surprisingly