Use `<msubsup>` in integral markup, not `<munderover>`

[samimaattaCelia]

I noticed that integrals shouldn't be marked up with <munderover>, but with <msubsup>. This way the rendering is correct. This is also the way it is demonstrated in MathML 3 and MathML 4.

There are in Firefox:

<munderover>:

vs.

<msubsup>:

[samimaattaCelia]

Also how do you markup the "dx"?

[no invisible times]
<mi>d</mi>
<mi>x</mi>

2. (This was in MathML 3).

<mo> &#x2062;<!--INVISIBLE TIMES--> </mo>
<mo>d</mo>
<mi>x</mi>

[no invisible times]
<mi>dx</mi>

<mspace width="0.25em"/>
<mi>dx</mi>

5. (MathCAT tests.)

<mtext> </mtext>
<mi>d</mi>
<mi>x</mi>

Or something else? The point

[MartheGjelstad]

I think I would use
<mi>d</mi><mi>x</mi>

I tried the different alternatives in Firefox and Edge, and I think this alternative looks correct.
Also, d is kind of Δ, which is a representation for a length. Therefore, I don't think "d" is an operator and shouldn't be a <mo> element.

[samimaattaCelia]

What woud you use for the spacing? <mo>[invisible times] </mo> (like for units) or <mspace>?

[MartheGjelstad]

I don't think I would use any space...

[samimaattaCelia]

To my eye it seems more common than not to have whitespace between the function and "dx".

[MartheGjelstad]

Then I think I would use the following markup:

<msubsup><mo>∫</mo><mi>a</mi><mi>b</mi></msubsup> <mrow><mi>f</mi><mo>(</mo><mi>x</mi><mo>)</mo></mrow><mo rspace="0.25em">&#x2062;</mo><mi>d</mi><mi>x</mi>

"dx" is a replacement for the "Δx" in Riemann sums. Therefore, I think it will be mathematically correct to use invisible times.
I would use an <mrow> around the integrand. Should it be around "dx" as well?

Maybe the markup in the MathML 3 is correct? I am not sure if "d" is an operator, and should be a <mo> element.

[MartheGjelstad]

1. normal latin d as <mi> element
2. normal latin d as <mo> element
3. double-struck italic d as <mo> element. Output from MathCAT: ... "double struck italic d x"

All examples:

• <mrow> around integrand and "dx". Visually and for the output from MathCAT, it doesn't matter if the <mrow>s are there or not.
• <mo rspace="0.25em">&#x2062;</mo> between the integrand and "dx".

My proposed solution:

• d as a <mi> element
• <mo rspace="0.25em">&#x2062;</mo> between integrand and "dx".
• I don't think it's that important whether there are <mrow>s around the integrand and "dx" or not.