Reading the chevrons and using Hold

The chevrons work exactly as in Ditching — see Ditching → Auto-grading the ditch for the full chevron rules. The Inches Per Chevron setting (Settings → GRADING) controls the step size in the same way.

The top stats bar in Manual Grade:

• Current (ft) — your machine's elevation in the survey frame (GPS altitude + benchmark offset).
• Target (ft) — the design elevation at your current station along the active segment.
• Grade — the active segment's grade percent and direction (e.g. "0.30% ↓").
• Seg N/M — segment chip; N is the active segment, M is the total segment count for the job. Only shown when M ≥ 2.
• BM badge — same calibration shortcut as elsewhere.

Hold / Release — works the same as in Ditching. Tap Hold to halt the hydraulics without exiting; Release re-engages auto-grading. Raise / Lower remain live during Hold for hand-jogging.

Start is GPS-gated. Tapping Start with no GPS fix or a stale GPS feed shows a red SnackBar (No GPS fix / GPS: STALE — position not updating) and grading does not start; the simulator is exempt. If the fix drops while the Ready to Start? dialog is open, tapping START shows an orange SnackBar (GPS fix lost while confirming. Reference not captured — try again when GPS is back.) and the 0+00 reference is not captured — try again once GPS returns. A reference is also refused with a red SnackBar if the GPS coordinates are invalid.

Pre-Start safety check. The reference-distance warning fires when you first tap Start too far from 0+00. The elevation-mismatch dialog is off by default; if you have switched it on (Settings → PRE-START SAFETY → Elevation Mismatch Check) it fires on that first Start as well. On a Resume, the manual-distance sub-check is skipped because you're intentionally resuming where you stopped; the elevation sub-check, if switched on, still fires.

Auto-Hold. Same trigger list as Ditching — non-RTK fix, GPS stale, HDOP above the per-sensitivity threshold, rolling-window degradation on Mid/High sensitivity. The RTK-quality triggers are gated by the RTK Filter (Settings → SURVEY); the GPS-stale and no-fix triggers always fire. Simulator mode bypasses Auto-Hold.