SD_NONE
{ SD_NONE, NULL, 0, NULL, 0, NULL }
for (size_t i = 0; specialdays[i].id != SD_NONE; i++) {
for (size_t i = 0; specialdays[i].id != SD_NONE; i++) {
for (size_t i = 0; specialdays[i].id != SD_NONE; i++) {