C1C[13C]1(=O)[O-]
ATOM1(,C,,,)
ATOM2(,C,,,)
BOND(,1,2)
ATOM3(13,C,,0,0)
BOND(,2,3)
BOND(,1,3)
ATOM4(,O,,,)
BOND(=,3,4)
ATOM5(,O,,0,-1)
BOND(,3,5)