texmath-0.13: test/writer/mml/invChars.test

<<< native
[ ENumber ""
, EMathOperator ""
, EIdentifier ""
, ESymbol Ord "\8290"
, ENumber ""
, ESymbol Ord "\8289"
, ESpace (0 % 1)
]
>>> mml
<?xml version='1.0' ?>
<math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <mn></mn>
    <mrow>
      <mi mathvariant="normal"></mi>
      <mo>&#8289;</mo>
    </mrow>
    <mi></mi>
    <mi>&#8290;</mi>
    <mn></mn>
    <mo>&#8289;</mo>
    <mspace width="0.0em" />
  </mrow>
</math>