demagnetize Aiken 2-frequency coherent phase- Known as F2F, this is the encoding technique used for cards meeting ISO standards ISO/IEC-7811-2 (see figure 7) and ISO/IEC-7811-6. Each "0" bit has a flux change at the beginning and end but not in the middle. A "1" is similar except that there is a flux transition in the middle of the bit.