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Old 08-29-2013, 06:46 AM   #24
Peter (Biopython etc)
Location: Dundee, Scotland, UK

Join Date: Jul 2009
Posts: 1,541

Originally Posted by NikTuzov View Post

I have a question about the so-called Sanger format where Q can be in [0;93] represented by [!-~]. Since this is the set of all visible ASCII characters, then it looks like there is no symbol reserved for a missing value. Does it mean that specifying missing values for the quality of individual base pairs is impossible? If yes, why?
Yes, although in this case you could use PHRED quality 0 (and I recall some tools may use the upper bound 93 as a special value).

Why? None of the early technologies needed a missing value quality score.
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