Extracting a Part of a Single Reference Sequence
If a single reference sequence is specified using the `-s' option or if the input mapping contains only a single reference sequence, the `-b' option may be used to specify a position range to extract. The output mapping will then only contain matches to this specific region. If a match is partially located in the region, only the part of the match inside the region is kept.
This option is useful for studying a particular section of a long reference sequence. It could, for example, be a single gene in the whole human genome.