FAST timing residuals of PSR J0435+3233 based on the ELL1H model (see Table 1). Panel (A) shows the timing residuals across the observation dates (in MJD). Panels (B) and (C) show the residuals as a function of inner orbital phase (measured from the ascending-node passage) with and without considering the Shapiro-delay parameter h₄ in the timing model. The corresponding fourth harmonic terms are also indicated by the red line. The expected peak phase of the Shapiro-delay term is 0.25 when all harmonics are included.