Clustlw alignment of a typical PacBio ccs read from Marshall et al . [] with the top two blastn matches (nr). The quality score is shown graphically (log scale) above the PacBio ccs read (m12705_051145…s1/8/ccs) and ranges from 9 (positions 81 to 84) to 93, with an average of 78.6. The dashed line indicates a quality score of 23, equivalent to an accuracy of 99.5%. Note that regions with low quality scores are associated with homopolymers, but homopolymers do not always have low quality scores. The processed long read from which this specific ccs sequence was generated was 4944 nt long, with a quality score that ranged from 0 to 15 and averaged 10.3. The length equates to approximately 9.5× single-molecule coverage.