Heng Li from the Sanger Institute wrote most of the initial source codes of SAMtools and various converters. Bob Handsaker from the Broad Institute is a major contributor to the SAM/BAM specification. He designed and implemented the BGZF format, the underlying indexable compression format for the BAM format. BGZF does not support arithmetic between file offsets. Jue Ruan for the Beijing Genome Institute designed and implemented the RAZF format, an alternative indexable compression format. RAZF supports arithmetic between file offsets, at the cost of increased index file size and the full compatibility with gzip. RAZF is optional and only used in `faidx' for indexing RAZF compressed fasta files. Colin Hercus updated novo2sam.pl to support gapped alignment by novoalign. Petr Danecek contributed the header parsing library sam_header.c and sam2vcf.pl script and added knet support to the RAZF library.