Registration,indexingandsearchingofchemicalstructuresinrelationaldatabasesisoneofthecoreareasofcheminformatics[1,2].Researchonthetopicgoesbacktothe1960sandprobablybeforethat[3].However,littledetailhasbeenpublishedontheinnerworkingsofsearchenginesanddevelopmentshavebeenmostlyclosedso