I noticed this change too, and I agree with Dan. Either keep 'iff' or replace with 'if and only if'lav at etersoft.ru wrote:- replace 'iff' with 'if' (just a spelling fixes)'iff' is shorthand for 'if and only if'. http://en.wikipedia.org/wiki/If_and_only_if So many of those 'typos' might actually be correct. Careful! - Dan