Synonyms: Indigosol O4B (6CI); [2,2'-Bi-1H-indole]-3,3'-diol, 5,5',7,7'-tetrabromo-, bis(hydrogensulfate) (ester), disodium salt (9CI); [2,2'-Biindole]-3,3'-diol,5,5',7,7'-tetrabromo-, bis(hydrogen sulfate) (ester), disodium salt (8CI);Ahcovat Soluble Blue O 4B; Algosol Blue O 4B; Anthrasol O 4B; Arlindone Blue O4B; C.I. 73066; C.I. Solubilised Vat Blue 5, disodium salt; Chemisol Blue O 4B;Cibantine Blue 2B; Fenanthra Blue O 4B; Indigosol Blue O 4B; Kambosol Blue O4B; Sandozol Blue O 4B; Shikiso Indigosol O 4B; Solasol Indigo 4B; Soledon Blue4BC; Soledon Blue O 4B; Solindolo Blue 2B; Soluble Vat Blue 2B; Solvat Blue 4B;Tinosol Blue O 4B