High proper-motion sequence (HPMS) in the [Fe/H]-L_Z plane from various samples. Only stars with Z_max > 2 kpc are shown. (a) Photometric sample with proper motions exceeding 60 mas yr⁻¹. Metallicities were estimated via Bayesian inference using SDSS and SMSS photometry, and L_Z values were computed along the Galactic prime meridian without radial velocity information. (b) Schematic locations and extents of major stellar populations for reference. (c, d) Medium-resolution spectroscopic samples from SDSS and LAMOST, respectively, showing metallicities against L_Z derived from full space motions. Stars with proper motions exceeding 20 mas yr⁻¹ in SDSS and 40 mas yr⁻¹ in LAMOST were selected. (e, f) High-resolution spectroscopic samples from GALAH and APOGEE, respectively, limited to stars with proper motions above 20 mas yr⁻¹. For these samples, L_Z values were also computed using complete kinematic information.