Landed = the dogleg the string SITS in; kept low (~2°) so the rotating shaft & couplings don't fatigue. Run-in = the sharpest dogleg it PASSES THROUGH (transient — recommend ≤6°, run to ≤12°), bounded by the housing-neck bending surviving the bend (carbon-steel E = 30×10⁶ psi). The string is modeled as rigid housings (pumps · separator 4.5′ · seal 6′ · motor) that bend at the flanged necks between them. Pump stiffening % credits the shaft/stage stack's added bending stiffness (motors, seals & separators use fixed built-in assumptions). Extra weight below motor adds hanging-weight (axial tension) from anything hung off the motor's bottom — a desander, sensor sub, etc. — that isn't otherwise modeled. Risk line is the working limit that pass/fail checks are graded against (default 25,000 psi — real bolted-flange necks usually fail at the bolts, not the tube section this model computes, and bolt count/metallurgy varies by vendor, so treat this as adjustable). Yield line is a second, more severe reference only (default 44,000 psi, from real field bending-failure data) shown on the charts for context — it does not gate any checklist result.