Before you start

The prerequisites are the same as any auto-grading mode, with two qualifiers:

1. A control link. Either a Ditch Assist Control Module paired over Wi-Fi, the built-in simulator, or the DIG module (Excavator only). Bluetooth GNSS alone is not enough — Bluetooth is for surveying, not for driving the blade.
2. RTK Fixed GPS. The Accuracy badge in the top stats bar should read RTK Fixed (green) — the only fix quality endorsed for grading. RTK Float is not endorsed (continuing on it is at your own risk); no fix means no grading.
3. A calibrated benchmark. Tap the BM badge in the stats bar before tapping Start. Manual Grade does not open a benchmark prompt automatically — calibrate from the BM badge or from a different workflow that does prompt.
4. Correct blade height (Settings → SURVEY → Blade Height), for non-DIG sources. DIG already provides bucket-tip-corrected elevation, so blade height is not used in that path.

About 0+00

The 0+00 reference is the GPS position the app captures when you first tap Start. From there the target elevation is computed as start_elevation − depth_offset ± grade × distance_from_0+00. The Depth Offset (entered in the Set Grade bar, positive only) drops the whole design line below the elevation captured at Start — with a 6″ offset the blade targets 6″ below where it sat when 0+00 was locked, then follows the grade from there. Depth Offset is per-segment and is saved and restored with the job. There is no terrain to interpolate against — the slope continues forever in both directions. If you anchored the slope at the wrong spot, Reset and start over.