Stacked F814W WFC/ACS image of the SMC field that includes the clusters NGC 346 and BS 90, which are highlighted by the azure and red circle, respectively (left). The middle panel shows the proper-motion diagram, while the m_F814W vs. m_F555W − m_F814W CMD is represented in the right panel. Only stars in the F814W magnitude interval between the two horizontal lines in the CMD are plotted in the proper-motion diagram, where the stars in the NGC 346 and BS 90 regions defined in the left panel are colored blue and red, respectively. Blue and red symbols in the right-panel CMD mark proper-motion selected cluster members in the NGC 346 and BS 90 regions. See text for details.