Synonyms: 2H-1,4-Benzothiazine-6-carboxylic acid, 3,4-dihydro-3-oxo-; 3-Oxo-3,4-dihydro-2H-benzo[1,4]thiazine-6-carboxylic acid; 3,4-Di hydro-3-oxo-2h-benzo[1,4]thiazin-6-carboxylic acid; 3-keto-4H-1,4-benzothiazine-6-carboxylic acid; 3-oxo-4H-1,4-benzothiazine-6-carboxylic acid;