In releasing all these sequences, GRC did not provide a canonical naming scheme for these sequences, nor did it impose a particular ordering of the sequences. This presents a problem in bioinformatics, as all file formats (SAM/BAM, VCF, GFF, BED, etc.) require a unique string identifier when referring to a particular sequence. Everything from read mappings, to variants, to genomic annotations (such as dbSNP or gene databases) needs to identify its genomic location by sequence name and coordinate. This freedom lead to different conventions being adopted by different teams.