Sprott–Linz Case U — Linz–Sprott 1999 piecewise-linear jerk. dx/dt=y, dy/dt=z, dz/dt=−a·z−y+|x|−1. Classic a=0.6 (b=1 fixed). Dual a+scale sliders (scale chrome-only). Display embed (x,y,z). Distinct from sprott-linz-a…t.html, sprott-jerk.html (quadratic y² jerk), sprott.html. Bulk centroid ≈ (−0.6803, 0.0111, 0.0108). RK4 chaotic fold. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.