101.110 i sent this and it arrived at the other end as 010. is this a code that is in this set? no it isnt if you try with these just changing any one of the bits and flipping it either a 1 to a 0 or a 0 to a 1 you endup with something that isnt in this list of good valid codes, you could say well there are bad codes there are things that don't correspond to any of these and of course with 3 bits 2 to the power of 3 is 8 so there are 8 possible combinations, what we have done is split them in to 4 good codes that are meaningful and 4 bad ones. 