These elements can be allowing particles to pass through like E-wall.

正在重建 /PowderToy/3/115.html ...

Element number 115 (INVS) usage:
  * .tmp = minimum pressure threshold.
    * default value = 4 (some as sim_max_pressure)
  * Invisible to particles while under pressure.
  * turns PROT into NEUT.

正在重建 /PowderToy/4/192.html ...

Note: "PINV" is experimental.
Element number 192 (PINV) usage:
  * PSCN activate, NSCN deactivate.
  * Invisible to particles while activated.
  * .tmp4 = another pmap (try creating a second pmap)?
  * Note: This element is pressure-insensitive.