Extra mrow within a math tag

Do we want an extra mrow within a math tag to hold semantic information?

Consider the following example:

Original MathML:

<math>
  <mi>a</mi>
  <mo>+</mo>
  <mi>b</mi>
  <mo>+</mo>
  <mi>c</mi>
</math>

Version 1 of semantically enriched MathML:

<math>
  <mrow type="infixop" role="addition" id="5" content="1,3" children="0,2,4">
    <mi type="identifier" role="latinletter" id="0" parent="5">a</mi>
    <mo type="operator" role="addition" id="1" operator="infixop,+" parent="5">+</mo>
    <mi type="identifier" role="latinletter" id="2" parent="5">b</mi>
    <mo type="operator" role="addition" id="3" operator="infixop,+" parent="5">+</mo>
    <mi type="identifier" role="latinletter" id="4" parent="5">c</mi>
  </mrow>
</math>

Version 2 of semantically enriched MathML:

<math semantic-type="infixop" semantic-role="addition" semantic-id="5" semantic-children="0,2,4" semantic-content="1,3">
  <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="0" semantic-parent="5">a</mi>
  <mo semantic-type="operator" semantic-role="addition" semantic-id="1" semantic-operator="infixop,+" semantic-parent="5">+</mo>
  <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="2" semantic-parent="5">b</mi>
  <mo semantic-type="operator" semantic-role="addition" semantic-id="3" semantic-operator="infixop,+" semantic-parent="5">+</mo>
  <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="4" semantic-parent="5">c</mi>
</math>