diff --git a/restoration/source410/BT_L4/GAUGE-BLOCK.NOTES.md b/restoration/source410/BT_L4/GAUGE-BLOCK.NOTES.md
index 51fd72eb..2b53e496 100644
--- a/restoration/source410/BT_L4/GAUGE-BLOCK.NOTES.md
+++ b/restoration/source410/BT_L4/GAUGE-BLOCK.NOTES.md
@@ -854,8 +854,8 @@ big overlapping defect makes a small one measure as noise -- or worse, as
 already-optimal, which is what I recorded.
 
 WHAT IS LEFT, LARGEST FIRST:
-  * sec (325 missing / 1039 extra) -- the 3-D scene head.  This is btl4vid,
-    the world renderer, and the next big climb; the gauge work cannot move it.
+  * sec -- the COLOUR RADAR head (NOT the 3-D scene; see the 5.3.39 note).
+    Ordinary gauge work, and now the largest single head delta.
   * Comm (2099 missing / 0 extra) -- content the shipped Comm page draws that
     we never build at all.  Zero extra means nothing we draw there is wrong,
     so this is a build-it wave, not a fix-it one.
@@ -900,9 +900,20 @@ FailureTemperature / CoolantMassLeakRate) are published in HEAT.CPP.
 
 WHAT IS STILL OPEN, IN THE ORDER I WOULD TAKE THEM:
 
-  1. sec (417 missing / 670 extra) -- the 3-D scene head.  This is btl4vid,
-     the world renderer, and no amount of gauge work moves it.  The next big
-     climb, and the last one.
+  1. sec (417 missing / 670 extra) -- CORRECTED: this is the COLOUR RADAR
+     head, NOT the 3-D scene.  Port 0 carries map / headingPointer /
+     digitalClock / numericSpeed / messageBoard / the armour colour-mappers
+     / the four GeneratorClusters (widget map), and its plate shows the radar
+     scope, the SPEED / HEADING / MISSION TIME dials and the ARMOR DAMAGE
+     diagram.  It is the pod's colour screen -- the "5 mono MFDs + colour
+     radar in one 16bpp buffer" the VDB splits.  So this is ordinary gauge
+     work, and it is now the largest single head delta.
+
+     btl4vid is a SEPARATE deliverable this rig cannot measure at all: the
+     3-D main view never enters the gauge framebuffer.  It goes down the dPL
+     retained-scene path to the render board (port 0x150 wire), and these
+     confs run L4VIDEO=OFF, so it is not even being produced.  Measuring it
+     needs the render bridge, not planes.py.
 
   2. The leak-gauge hatch (~480px, and the bulk of what is left on Heat and
      the MFDs).  CORRECTED after checking both of my own guesses: