MathML not accepted as valid content for heading (h4) element

[francofaa]

Ace 1.3.2, Ace by DAISY app

The error was Minor, Best Practice, empty-heading with the text

• Element does not have text that is visible to screen readers
• aria-label attribute does not exist or is empty
• aria-labelledby attribute does not exist, references elements that do not exist or references elements that are empty
• Element has no title attribute
• Ensures headings have discernible text
• Headings should not be empty

The content of the heading (with additional context) was

        <section class="level3" data-cfititle="Rate = k[A] superscript 2" epub:type="level3" id="rev_9781319369859_ch13sectlev3sect01">
          <header id="pijaf13cbae91e8ea35ad1b541f0f663">
            <h4 class="c-head title" epub:type="title" id="qago2378c123cf4da25e836845e9b1d8">
              <span class="math" id="xper68cbdedf377ee0e4de6d4337af88" tabindex="0">
                <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="text Rate  end text equals text italic k  end text not stretchy left square bracket text A  end text not stretchy right square bracket squared" display="inline" id="jphgcf738586b6209c9f961417b2fd63">
                  <semantics id="gjurdc99812fc14bab64e63242193f46">
                    <mrow id="yfkf0ee251bfa4da2c7bd866769f053c">
                      <mstyle id="mxoq80182f3e42bdc05302be6c5d3a19">
                        <mtext id="dxppf250498f426f7efcfbb84befea60">Rate </mtext>
                        <mo id="yjbcf7c22feff82037288ad2cc32c6bc">= </mo>
                        <mtext id="wspba9069b6bea20a7c63ee88c7adcec" mathvariant="italic">k </mtext>
                        <msup id="cxjaade89fe54f36513b87b6eb8be41f">
                          <mrow id="ehdc2d73ee5e303e7cb35fa9411024f5">
                            <mo id="qnhlc9a9497412179387946e0d9b6385" stretchy="false">[ </mo>
                            <mtext id="mlbr6468b7d5201461b8284b5987c4f0">A </mtext>
                            <mo id="kxrc0777fcdfeaa46e954ecf05704ae5" stretchy="false">] </mo>
                          </mrow>
                          <mn id="isfha59ad564151653d0ee82404b19b2">2 </mn>
                        </msup>
                      </mstyle>
                    </mrow>
                    <annotation-xml encoding="application/xhtml+xml" id="naxy4d6f367df4508f767c057d1bfd55" name="alternative-representation">
                      <img xmlns="http://www.w3.org/1999/xhtml" alt="text Rate  end text equals text italic k  end text not stretchy left square bracket text A  end text not stretchy right square bracket squared" id="cyioff1e022e8f06035f24dd16aa6397" src="../images/jphgcf738586b6209c9f961417b2fd63.png"></img>
                    </annotation-xml>
                  </semantics>
                </math>
              </span>
            </h4>
          </header>

It appears that the MathML is being read as no text or as inaccessible text. This may be related to issue 398.

Thank you for any assistance that can be provided.

[danielweck]

This is a known issue with Deque Axe, I have tried to implement missing parts in Axe's code but I am lacking some understanding of Axe's internals (plus, I started exploring this issue from a slightly older revision of the Axe codebase which was used by DAISY Ace at the time). Here is the relevant issue at the Axe GitHub repository: dequelabs/axe-core#3285