1-oxa-2-azaspiro[4.5]deca-2,6-diene-3-carboxylic acid, 9,10-dihydroxy-8-oxo- 9,10-dihydroxy-8-oxo-1-oxa-2-azaspiro[4.5]deca-2,6-diene-3-carboxylic acid InChI=1/C9H9NO6/c11-5-1-2-9(7(13)6(5)12)3-4(8(14)15)10-16-9/h1-2,6-7,12-13H,3H2,(H,14,15