Synonyms: 1H-Indol-3-ol,2-[9-chloro-3-(sulfooxy)naphtho[1,2-b]thien-2-yl]-, hydrogen sulfate (ester),disodium salt (9CI); Indol-3-ol,2-(9-chloro-3-hydroxynaphtho[1,2-b]thien-2-yl)-, bis(hydrogen sulfate) (ester),disodium salt (8CI); Naphtho[1,2-b]thiophene, 1H-indol-3-ol deriv.; AnthrasolBlue Black IRD; C.I. 73661; C.I. Solubilised Vat Black 6, disodium salt