FLD with derived flux; moving cases include first-order gas/radiation evolution and lab-frame enthalpy transport. Available analytic references solve qualified linear diffusion-limit problems; their discrepancy norms cover the projected slice, not the full volume. Thin positive-opacity streaming cases have no supplied analytic spatial FLD reference and instead check exact periodic energy integrals.
Coupled radiation hydrodynamics. These numerical profiles have no supplied analytic reference or accuracy norms.
First-order mixed-frame gas/radiation evolution with physical light speed. Derived lab-frame flux includes radiation enthalpy advection. No independent analytic or digitized reference profile is supplied; M1 differences are model discrepancies.
Mixed-frame FLD with first-order gas transport and backward-Euler diffusion/material exchange; physical c = 29979245800 cm/s. Radiation flux is the derived lab-frame diffusion plus enthalpy-advection flux; it is not an independently evolved momentum variable. No independent analytic or digitized FLD reference profile is supplied. M1 versus FLD differences compare distinct radiation models and are not analytic-reference errors.
Central cell layer at z=dx/2; ray at y=z=dx/2.

