The Missing Siman
In 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.
He said,his reasoning was ,so that people will realize, a) that one may
change ones mind and b) not to print Toires that are not Emes.