The International Society of Genetic Genealogy (ISOGG) maintains the most up-to-date consensus version of haplogroup categories. These classifications are based on shared SNP mutations. The discovery of new SNPs can result in assignment of new names to haplogroup categories. There were only a few G categories until 2008 when major revisions to categories were made. Even more G SNPs were identified in 2009 to 2012 leading to more changes. Until 2008, new G SNPs were reported from labs at the University of Arizona (P designations), Stanford University (M designations) or the University of Central Florida (U designations). Beginning in 2008, additional G SNPs were identified at Family Tree DNA (L designations) and Ethnoancestry (S designations). These latter labs also made use of raw data results reported by individuals tested for about 2,000 SNPs at 23andMe to provide new L or S-designated SNP tests. In 2009-10, Family Tree DNA's Walk through the Y Project, sequencing certain Y-chromosome segments, provided a number of new G SNPs with the L designation. In 2012, SNPs with the Z designation as first identified by citizen researchers from 1000 Genomes Project data began to appear.