Issues regarding nomenclature are more controversial than scientific ones, as there is never one correct answer, and some aspects are matters of opinion and taste. In 1978, Kornfeld presented a system for symbolic representation of vertebrate glycans, which enjoyed popular use and was eventually adopted and standardized for the first edition of the Essentials of Glycobiology textbook (1999). While this adoption increased usage, the system had limitations and inconsistencies, and did not use color. Anticipating upcoming work on a second edition, the editors developed an updated nomenclature, which was made available to the community in 2004 before publication, and was adopted and widely disseminated, especially by the NIGMS-funded Consortium for Functional Glycomics (sometimes resulting in the incorrect term "CFG Nomenclature"). Moreover, even after the final publication of the Second Edition in 2009, acceptance by the community remained incomplete, and individual variations began to appear. Anticipating preparation of a third edition, a reorganized group of Essentials editors (supported by the NHLBI-funded Programs of Excellence in Glycoscience) agreed on an updated symbol nomenclature that went beyond vertebrate glycans, considered input from others using related systems, coordinated with the IUPAC Carbohydrate Nomenclature committee, linked each monosaccharide symbol to the corresponding entry in PubChem at NCBI/NLM, and initiated coordination with other long-term online resources. The system became an online advance Appendix to the Third Edition of Essentials. New symbols were added, but to ensure compatibility with prior publications, no changes were made to symbols in the Second Edition. For this historical reason, shapes and colors are internally consistent only for some monosaccharides. Symbol colors are specified in CMYK and RGB settings. Linkages can be shown as in the Second Edition system using IUPAC style, with the originating carbon assumed, and hyphens (not commas) used as an option. The Oxford system of angled monosaccharide linkages with embedded specificity and anomericity can also be used. Details on all aspects can be found in the notes to the Essentials Appendix at NCBI, which also contains many other useful links. Symbols also have embedded information such as links to PubChem, and are available in downloadable files as high quality objects.
Realizing the need for a standard acronym, the Essentials editors then suggested SNFG: Symbol Nomenclature For Glycans. This generic name recognizes the fact that while the update arose from the editors’ need to standardize a previous system for the third edition of a textbook, many others eventually contributed towards its final creation, and the system thus belongs to the community. Accordingly, a broadly representative SNFG Discussion Group now works with the NCBI on periodic updates. If the system gains wide acceptance in the literature and is adopted by major journals, there is a possibility of a separate SNFG Website, likely linked to PubChem. This is another step towards mainstreaming of glycan bioinformatics, to become an integral part of the molecular and cellular bioinformatics of all living systems.
Following the initial release in 2015, the SNFG discussion group has worked with the NCBI and Pubchem to generate the updates as shown in Updates.