Projected Rayleigh statistic Z (top row; Equation (7)) and per-pixel alignment components z_i (bottom row; Equation (13)) as a function of column density. Blue shading/empty circles indicate subfilaments, while green shading/gray crosses indicate the DR21 Main Ridge. Columns show the relative orientation between magnetic field and intensity gradient (left; Section 4.1), self-gravity and intensity gradient (middle; Section 4.2), and magnetic field and self-gravity (right; Section 4.3). For Z, error bars give σ_obs(Z) (Equation (12)), reflecting individual measurement uncertainties, while shading gives σ_gen(Z) (Equation (11)), our preferred uncertainty measure that also captures internal structural diversity (Section 3.4). An inset legend in the upper right panel illustrates both uncertainty types. For z_i, dashed lines connect bin-averaged 〈z_i〉 values and shading indicates σ_gen(〈z_i〉).