Bottom-left panel: NGC 6656 V vs. (V − K_S) CMD for all stars in our catalog (black dots) that have a membership probability measure. We plotted variable stars from Kaluzny & Thompson (2001) with green triangles that are cross-identified in our catalog with P_μ < 2%; yellow squares represent the star with 2% ≤ P_μ < 75%. The azure circles are those stars with P_μ ≥ 75%. Bottom-right panel: V vs. P_μ. Top: VPD. We also drew proper motion error bars for matched variable stars.