diff --git a/display-board-1408.md b/display-board-1408.md
index 2fb40cc6..a42b3afc 100644
--- a/display-board-1408.md
+++ b/display-board-1408.md
@@ -104,7 +104,11 @@ also the RIO's **error annunciator**:
   count (`$3185`, `$DA2F`). Each increment site immediately re-renders,
   so the display live-updates as serial trouble accumulates. If a
   cockpit's display reads `E0…` instead of `F0000000`, the serial link
-  has been dropping or retrying.
+  has been dropping or retrying. Note there is **no threshold in stock
+  firmware** — the first event paints `E0000001` permanently; the
+  `_e0t5` patched images (`make_patch.py --e0thresh`, see
+  [RIOv4_2-ANALYSIS.md](../../rio-firmware/RIOv4_2-ANALYSIS.md)) keep
+  the display quiet until a counter reaches 5.
 - **`dEAd` crash screen** (`$DAB8`, loop at `$DAB2`) — the TX-ISR ring
   drain (`$D8C2`) looks each outgoing command byte up in an 8-entry
   dispatch table at `$3158`; an unmatched byte means internal state