Synonyms: Spiro[2H-1-benzopyran-2,2'-indoline],1',3',3'-trimethyl-6-nitro- (6CI,7CI,8CI);1,1,3-Trimethyl-6'-nitrospiro[indoline-2,2'-benzopyran];1,3,3-Trimethyl-2-(6-nitrospirobenzopyran-2-yl)indoline;1,3,3-Trimethyl-2-indolino-2'-spiro-6'-nitrobenzo[b]pyran;1,3,3-Trimethyl-6-nitroindoline-2-spiro-2,2-benzopyran; 1,3,3-Trimethyl-6-nitrospiro(2H-1-benzopyran-2,2'-indoline);1,3,3-Trimethyl-6'-nitroindoline-2-spiro-2'-benzopyran;1,3,3-Trimethyl-6'-nitrospiro(indolino-2,2'-benzopyran);1,3,3-Trimethyl-6'-nitrospiro[indole-2,2'-benzopyran];1,3,3-Trimethyl-6'-nitrospiro[indoline-2,2'(2'H)-chromene];1,3,3-Trimethyl-6'-nitrospiro[indoline-2,2'-benzopyran];1,3,3-Trimethylindolino-6'-nitrospirobenzopyran;1',3',3'-Trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-indoline];1',3'-Dihydro-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-[2H]indole];2H-Spiro[6]nitrochromene-2,2'-[1,3,3]trimethylindoline;6-Nitro-1',3',3'-trimethylspiro[1H-1-benzopyran-2,2'-indoline];6-Nitro-1',3',3'-trimethylspiro[2H-1-benzopyran-2,2'-indoline];6-Nitro-1',3',3'-trimethylspiro[2H-benzopyran-2,2'-indoline]; 6'-Nitro-1,3,3-trimethylspiro[2'H-1'-benzopyran-2',2-indoline];6'-Nitro-1,3,3-trimethylspiro[indoline-2,2'-2'H-chromene]; NSC 206176; SP 1; SP1 (dye)