Physical Integrity is correct of course, WHICH I beleive means ....
There is reference in the law of repairing vehicles, spec. firewall ***integrity*** can not be compromised, this means do not cut holes in the firewall to repair the AC or heater land glue it back together, IT IS the LAW in most states (CA) found one reference (looking for similar en other countries)
Firewalls are built between or through buildings, structures, electrical substation transformers, or within an aircraft or vehicle. ... Penetrations (holes) must not defeat the structural integrity of the wall, such that the wall cannot ...
https://en.wikipedia.org/wiki/Firewall_(construction)integrity of exhaust system not be defeated by cut out side exhaust, clamps instead of weld....etc Agree thats right physical integrity