Standard on‑center step for full‑body spaces (e.g., 3′6″).
If remainder ≥ this, add an extra Open at the midpoint. (Else see Minimum CO.)
Remainders in [Minimum CO, FB Minimum) become a CO. Remainders < Minimum CO are discarded; we retract the last step to avoid a sliver.
Add a new empty row or duplicate an existing one.
Tip: “Save” writes to a file if you’ve chosen one (via “Save As”). Otherwise it saves to this device (Projects list). You can still Export/Load JSON anytime.