+ EL_INVISIBLE_WALL,
+ EL_INVISIBLE_WALL_ACTIVE,
+ EL_SWITCHGATE_SWITCH_UP,
+ EL_SWITCHGATE_SWITCH_DOWN,
+ EL_TIMEGATE_SWITCH,
+ EL_TIMEGATE_SWITCH_ACTIVE,
+ EL_EMC_WALL_1,
+ EL_EMC_WALL_2,
+ EL_EMC_WALL_3,
+ EL_EMC_WALL_4,
+ EL_EMC_WALL_5,
+ EL_EMC_WALL_6,
+ EL_EMC_WALL_7,
+ EL_EMC_WALL_8,
+ EL_WALL_PEARL,
+ EL_WALL_CRYSTAL,
+
+ /* the following elements are a direct copy of "indestructible" elements,
+ except "EL_ACID", which is "indestructible", but not "solid"! */
+#if 0
+ EL_ACID,
+#endif
+ EL_STEELWALL,
+ EL_ACID_POOL_TOPLEFT,
+ EL_ACID_POOL_TOPRIGHT,
+ EL_ACID_POOL_BOTTOMLEFT,
+ EL_ACID_POOL_BOTTOM,
+ EL_ACID_POOL_BOTTOMRIGHT,
+ EL_SP_HARDWARE_GRAY,
+ EL_SP_HARDWARE_GREEN,
+ EL_SP_HARDWARE_BLUE,
+ EL_SP_HARDWARE_RED,
+ EL_SP_HARDWARE_YELLOW,
+ EL_SP_HARDWARE_BASE_1,
+ EL_SP_HARDWARE_BASE_2,
+ EL_SP_HARDWARE_BASE_3,
+ EL_SP_HARDWARE_BASE_4,
+ EL_SP_HARDWARE_BASE_5,
+ EL_SP_HARDWARE_BASE_6,
+ EL_INVISIBLE_STEELWALL,
+ EL_INVISIBLE_STEELWALL_ACTIVE,
+ EL_CONVEYOR_BELT_1_SWITCH_LEFT,
+ EL_CONVEYOR_BELT_1_SWITCH_MIDDLE,
+ EL_CONVEYOR_BELT_1_SWITCH_RIGHT,
+ EL_CONVEYOR_BELT_2_SWITCH_LEFT,
+ EL_CONVEYOR_BELT_2_SWITCH_MIDDLE,
+ EL_CONVEYOR_BELT_2_SWITCH_RIGHT,
+ EL_CONVEYOR_BELT_3_SWITCH_LEFT,
+ EL_CONVEYOR_BELT_3_SWITCH_MIDDLE,
+ EL_CONVEYOR_BELT_3_SWITCH_RIGHT,
+ EL_CONVEYOR_BELT_4_SWITCH_LEFT,
+ EL_CONVEYOR_BELT_4_SWITCH_MIDDLE,
+ EL_CONVEYOR_BELT_4_SWITCH_RIGHT,
+ EL_LIGHT_SWITCH,
+ EL_LIGHT_SWITCH_ACTIVE,
+ EL_SIGN_EXCLAMATION,
+ EL_SIGN_RADIOACTIVITY,
+ EL_SIGN_STOP,
+ EL_SIGN_WHEELCHAIR,
+ EL_SIGN_PARKING,
+ EL_SIGN_ONEWAY,
+ EL_SIGN_HEART,
+ EL_SIGN_TRIANGLE,
+ EL_SIGN_ROUND,
+ EL_SIGN_EXIT,
+ EL_SIGN_YINYANG,
+ EL_SIGN_OTHER,
+ EL_STEELWALL_SLANTED,
+ EL_EMC_STEELWALL_1,
+ EL_EMC_STEELWALL_2,
+ EL_EMC_STEELWALL_3,
+ EL_EMC_STEELWALL_4,
+ EL_CRYSTAL,