The Sefer Chazon Ish (Taharos) Meseches Keilim,
Siman 13 comes after Siman 11, Siman 12 is missing .
Before the heading of Siman 13, it says "Siman 12 was
erased and is missing".( נמחק וחסר )
The Chazon Ish changed his mind on what he wrote and
held it was wrong.(in Siman12)
He removed the whole shtikel before it was printed.
The printers wanted to adjust the Simanim .
The Chazon Ish insisted not to do so, but to skip
Siman 12. and add the words נמחק וחסר,so that people
will learn some important lessons.
a) one may change his mind if he is wrong
b) not to print Toires that are wrong (not Emes)
(No need to be stuck with Falshkeit)