In CF, genomic DNA is heat-denatured and allowed to renature to a Cot value (Cot = DNA concentration x time x a factor based on the cation concentration of the buffer) at which the majority of repetitive elements have reassociated but single and low-copy elements remain single stranded.
The process of denaturing and allowing for reannealing of genomic DNA in CF (Colony Formation) separates repetitive elements from single and low-copy elements based on their relative stability at a specific Cot value.