param[0] = 1;
param[1] = 2;
spritelayout my_layout(a) {
    ground { sprite: param[a]; }
    building { sprite: a; }
}
param[0] = 3;
param[1] = 4;
item(FEAT_AIRPORTTILES, small_airport_tiles) {
    graphics { my_layout(1); }
}