data/mathematical/208.mml
<math xmlns='http://www.w3.org/1998/Math/MathML' display='inline'><semantics><mrow><msubsup><mi>ξ</mi> <mi>i</mi> <mi>μ</mi></msubsup><mo>=</mo><mo>±</mo><mn>1</mn></mrow><annotation encoding='application/x-tex'>\xi_{i}^{\mu}=\pm 1</annotation></semantics></math>