Adapting flatfile parsers for GenBank’s new accession formats


As previously announced, GenBank and other INSDC members will expand the accession formats used for sequencing projects by the end of this year. We’re introducing these new formats to accommodate the growth of Whole Genome Shotgun (WGS), Transcriptome Shotgun Assembly (TSA), and Targeted Locus Study (TLS) sequencing sequences. More details about those changes are available on NCBI Insights.

You may have to adjust your code and databases to accommodate the new formats’ longer length. In particular, the first line of the flatfile format, referred to as the LOCUS line, includes the “Locus Name” (usually identical to the accession number), which may now grow to as long as 20 characters. See section 3.4.4 of the GenBank release notes for examples of how the LOCUS line might change.

Since 2003, the GenBank release notes have recommended that flatfile parsers use a whitespace-separated tokens approach to accommodate changes like the one described in section 3.4.4. If your flatfile parsers rely solely on position, you may have to make modifications. From our internal testing, it appears BioPython and BioPerl properly handle most of the examples shown in section 3.4.4, and only have issues with the last theoretical examples where the sequence length no longer ends at position 40. We do recommend adjusting code to accommodate those theoretical examples for future-proofing.

Please write to the helpdesk with any questions about the new formats.

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