Synonyms: Naphtho[1,2-d]thiazolium,1-methyl-2-[2-[[1-(3-sulfopropyl)naphtho[1,2-d]thiazolin-2-ylidene]methyl]-1-butenyl]-,hydroxide, inner salt (8CI); Naphtho[1,2-d]thiazolium,2-[2-[(1-methylnaphtho[1,2-d]thiazol-2(1H)-ylidene)methyl]-1-butenyl]-1-(3-sulfopropyl)-,hydroxide, inner salt; Naphtho[1,2-d]thiazolium,2-[2-[(1-methylnaphtho[1,2-d]thiazol-2(1H)-ylidene)methyl]-1-butenyl]-1-(3-sulfopropyl)-,inner salt (9CI)