diff --git a/docs/re/structures/ui-blend-mode-measured.md b/docs/re/structures/ui-blend-mode-measured.md
index 6bb08864..48dbb40c 100644
--- a/docs/re/structures/ui-blend-mode-measured.md
+++ b/docs/re/structures/ui-blend-mode-measured.md
@@ -107,10 +107,35 @@ The second is within 8 px of `pteff12` @2×; the first matches nothing on the
 screen at either scale. Both are additive, so they do not change the answer, and
 neither is guessed at here.
 
-⚠️ **Reach.** Two screens, one session, one emulator. Every element on the two
-screens the port ships is in the table except the two above and `pteff10`, which
-did not appear as an identifiable quad. The title screen (build 4) was **not**
-captured.
+⚠️ **Reach.** Two screens, one session, one emulator. The title screen (build 4)
+was **not** captured.
+
+🔴 **The sentence that stood here was wrong, and `sylpheed-port` caught it
+(2026-08-31).** It read: *"Every element on the two screens the port ships is in
+the table except the two above and `pteff10`, which did not appear as an
+identifiable quad."* Counting an element as covered if it appears in the per-draw
+log **or** in a prose row of the summary table, what is actually missing is
+
+| screen | in neither |
+|---|---|
+| main menu | `pteff10` — as stated |
+| **`EXTRAS`** | `pteff10`, **`ptframe4`, `pteff21`, `pteff22`, `pteff23`** |
+
+**Five, not one**, and on `EXTRAS` the four extra ones are precisely the elements
+the port measures as the worst on that screen. A reader of the old sentence would
+have concluded the coverage was complete but for one unidentifiable quad.
+
+✅ **The cause is found and fixed** — Canary's vertex dump was capped at 8
+vertices, two quads, so `EXTRAS`' 24-index additive draw reported two of its six
+elements and the other four looked like elements the game never draws. See the
+2026-08-31 section below. The result rows were never wrong; the claim about what
+they covered was.
+
+⚠️ **And "every button" in the table above is a class generalisation**, in the
+page whose own instruction is to read it as per-element facts. It came from
+`ptbtn01f` on the main menu. Run 3 below raises it to five buttons plus the focus
+ring, individually, **on the main menu**; no `EXTRAS` button has been measured at
+all.
 
 ---