diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 159fb8e..ff8fbb1 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -378,4 +378,4 @@ rewriting the document.
 | 27 | Camera live view is the one video stream to the tablet: its own connection beside the boundary, paced to the link (≤ ~4 MB/s), never on the bus. Exception to 20 | **Proposed** | 2026-10-11 |
 | 28 | Every Orin → tablet sender caps its socket (`SO_MAX_PACING_RATE`, ~5 MB/s); unpaced bursts stall the USB link for seconds | **Proposed** | 2026-10-11 |
 | 29 | `svc-vision` is Python: camera pipelines and inference live in that ecosystem. Exception to 5 | Accepted | 2026-10-12 |
-| 30 | The car's CAN broadcast is the source for every displayed vehicle value. OBD-II (K-line, ISO 9141-2, through the Bluetooth ELM327) is calibration only, recorded beside the frames and never shown as the primary value; GNSS speed is shown beside the decoded speed, to show their error | Accepted | 2026-10-13 |
+| 30 | The car's CAN broadcast is the source for every displayed vehicle value. OBD-II (K-line, ISO 9141-2, through the Bluetooth ELM327) is calibration, recorded beside the frames; a value proven absent from CAN may be displayed from OBD-II, and keeps its `obd_` name either way. GNSS speed is shown beside the decoded speed, to show their error. The ELM is the Orin's only way onto the K-line, so DTC scans go through it too; it is reached over classic Bluetooth serial (SPP, no pairing), BLE only if it proves as easy | Accepted | 2026-10-13 |