HelenOS sources
U_PAGE_DOWN 142 kernel/genarch/src/kbrd/kbrd.c case U_PAGE_DOWN:
U_PAGE_DOWN 128 kernel/genarch/src/kbrd/scanc_at.c U_PAGE_DOWN, /* 0x7a */
U_PAGE_DOWN 224 kernel/genarch/src/kbrd/scanc_at.c U_PAGE_DOWN, /* 0x7a */
U_PAGE_DOWN 164 kernel/genarch/src/kbrd/scanc_mac.c [0x79] = U_PAGE_DOWN,
U_PAGE_DOWN 81 kernel/genarch/src/kbrd/scanc_pc.c U_PAGE_DOWN, /* 0x51 - Page Down */
U_PAGE_DOWN 171 kernel/genarch/src/kbrd/scanc_pc.c U_PAGE_DOWN, /* 0x51 - Page Down */
U_PAGE_DOWN 166 kernel/genarch/src/kbrd/scanc_sun.c [0x7b] = U_PAGE_DOWN, /* Page Down */
U_PAGE_DOWN 298 kernel/genarch/src/kbrd/scanc_sun.c [0x7b] = U_PAGE_DOWN, /* Page Down */
HelenOS homepage, sources at GitHub