Description of tailcurve (nucleotide proportion at individual cycles along the sequence read). With perfect random fragmentation, a given position and its associated base calls (consensus and variant) should be represented at multiple sequencing cycles. With high coverage, a particular base call will be present for that position at all or most cycles. Example: for a sequencing module of 25 cycles with several hundred (24 shown) overlapping reads covering the highlighted position, all the cycles are represented by 'G', with variant reads producing the 'T' at a handful of cycles (potential variant).