Odd and even parity signifies that the total of 1s in a bit string is an odd or even number (zero has even parity). If ``p'' is entered at #27.6, the aspiring pre-images will be automatically specified as those states with the given parity relating (at most) to the first 20 cells (where the remaining cells have value 0). The following prompt is presented,
enter odd-1, or even-(default):
Select odd or even parity. A further prompt allows the parity to relate to part only of the system size n, where n<=20, or part only of the first 20 cells.
enter part system size (default 10): (for a system size where n=10)
If a size x less than the system size n (or less than 20 if n>20) is entered, states with the given parity relating only to cell indices 0 to x (and where cell indices x+1 to n are equal to 0) will be selected.