Hashed circular fingerprints that encode each atom according to its atomic symbol and hybridization for path length 2, ECFP2; path length 4, ECFP4; and path length 6, ECFP6.
Source: PAC, 2016, 88, 239. 'Glossary of terms used in computational drug design, part II (IUPAC Recommendations 2015)' on page 246 (https://doi.org/10.1515/pac-2012-1204)