If the template strand has two or more identical nucleotides in a row, their complementary nucleotides will be added one after the other in the same flow step. The labels on the vertical axis of the flow-gram indicate how many of the same nucleotide in a row are detected; for example, where a peak for C extends into the 3 region, it indicates 3 Cs in a row, or CCC. How are two or more of the same nucleotide (in a row) detected in the flow-gram?