Parallel Markup
Raw PMathML
Enhanced PMathML
Content MathML
Maxima

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <semantics>
    <mo>&NotEqual;</mo>
    <annotation-xml encoding="MathML-Content">
      <neq/>
    </annotation-xml>
    <annotation encoding="SnuggleTeX">\[ \not= \]</annotation>
    <annotation encoding="LaTeX">\[ \not= \]</annotation>
    <annotation encoding="Maxima">operator("#")</annotation>
  </semantics>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <semantics>
    <mo>&NotEqual;</mo>
    <annotation encoding="SnuggleTeX">\[ \not= \]</annotation>
  </semantics>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mo>&NotEqual;</mo>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <neq/>
</math>

operator("#")