diff --git a/assets/contracts/checklists/z27ag-captures.json b/assets/contracts/checklists/z27ag-captures.json
index ff4656e..49126bd 100644
--- a/assets/contracts/checklists/z27ag-captures.json
+++ b/assets/contracts/checklists/z27ag-captures.json
@@ -1,6 +1,6 @@
 {
   "id": "z27ag-captures",
-  "version": 2,
+  "version": 3,
   "title": "Z27AG decoding captures",
   "about": "docs/impl/plans/Z27AG-CAPTURES.md",
   "mark_format": "<step> <action>[ #<n>] start|end for a span, <step> <action>[ #<n>] for a point",
@@ -447,6 +447,59 @@
           ]
         }
       ]
+    },
+    {
+      "title": "IMU calibration (module fixed in its final place)",
+      "steps": [
+        {
+          "id": "27",
+          "title": "IMU level, facing one way",
+          "do": "Parked on the flattest ground at hand, engine off or idling, nobody moving inside. Start, keep still 15 s, end.",
+          "finds": "which way is down for the IMU (with step 28, cancelling the ground's slope)",
+          "actions": [
+            {
+              "label": "imu level A",
+              "hold_s": 15
+            }
+          ]
+        },
+        {
+          "id": "28",
+          "title": "IMU level, turned round",
+          "do": "The same spot, nose the other way: a rough 180° will do. Still again, 15 s.",
+          "finds": "the second half of the level: the slope's tilt reverses, the mounting's does not",
+          "actions": [
+            {
+              "label": "imu level B",
+              "hold_s": 15
+            }
+          ]
+        },
+        {
+          "id": "29",
+          "title": "IMU pull-away, straight",
+          "do": "A straight, flat section. From standstill, a firm pull-away in 1st to about 30. Start as the clutch bites, end as you lift.",
+          "finds": "which way is forward for the IMU",
+          "actions": [
+            {
+              "label": "imu pull away",
+              "repeat": 3
+            }
+          ]
+        },
+        {
+          "id": "30",
+          "title": "IMU braking, straight",
+          "do": "The same section. From about 40, a firm (not emergency) stop. Start as you brake, end when stopped.",
+          "finds": "forward again, from the other side; also braking g",
+          "actions": [
+            {
+              "label": "imu brake",
+              "repeat": 3
+            }
+          ]
+        }
+      ]
     }
   ]
 }