Heliocentric radial velocity distributions for stars with successful velocity measurements (gray filled histograms; Section 2.1) in spectroscopic fields targeting the NE shelf (Table 1), including both M31 RGB stars and MW foreground dwarf stars. From top to bottom and left to right, the fields probe larger M31-centric projected radii, approaching the “tip” of the tidal shell pattern (Section 3.4). The black dashed lines show the velocity distribution of stars classified as likely M31 members by the probabilistic model of Escala et al. (2020b), which includes radial velocity as a membership diagnostic. This model mistakenly classifies NE shelf stars in field NE3 with MW-like velocities (v _helio ≳ −150 km s⁻¹; Section 3.1) as likely MW contaminants. Thus, we assigned stars with v _helio > −100 (−150) km s⁻¹ for the inner (outer) fields or spectral signatures of strong Na I λ8190 absorption as MW contaminants (red open histograms; Section 3.1).