+ EL_SP_TERMINAL,
+ EL_SP_TERMINAL_ACTIVE,
+ EL_SP_EXIT_CLOSED,
+ EL_SP_EXIT_OPEN,
+ 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_PILLAR_UPPER,
+ EL_EMC_WALL_PILLAR_MIDDLE,
+ EL_EMC_WALL_PILLAR_LOWER,
+ EL_EMC_WALL4,
+ EL_EMC_WALL5,
+ EL_EMC_WALL6,
+ EL_EMC_WALL7,
+ EL_EMC_WALL8,
+ 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_ACIDPOOL_TOPLEFT,
+ EL_ACIDPOOL_TOPRIGHT,
+ EL_ACIDPOOL_BOTTOMLEFT,
+ EL_ACIDPOOL_BOTTOM,
+ EL_ACIDPOOL_BOTTOMRIGHT,