developer.mozilla.org/en-US/docs/Web/MathML/Element/moveraccent
If true the over-script is an accent, which is drawn closer to the base expression.
If false (default value) the over-script is a limit over the base expression. <math xmlns="http://www.w3.org/1998/Math/MathML">
<mover>
<msub>
<mi>A</mi>
<mi>i</mi>
</msub>
<mo accent="false">¯</mo>
</mover>
</math>mo带有accent="false"标签并且mo里面的字符是¯(overscore)
在MathJax v3被转换为
<math xmlns="http://www.w3.org/1998/Math/MathML">
<mover>
<msub>
<mi>A</mi>
<mi>i</mi>
</msub>
<mo accent="true">―</mo>
</mover>
</math>
mo带有accent="true"标签,并且mo里的字符是―(dash).
前者是正常的,后者的$i$或$j$上面没有点!
如图所示:
$\bar i\;\overline i\;\bar j\;\overline j$
在MathJax中转换为
在MS word中转换为
在MathJax中,暂时的解决办法:- document.querySelectorAll('mover:not([accent])').forEach(e=>e.setAttribute('accent','false'))
The default value of accent is false, unless overscript is an <mo> element or an embellished operator (see Section 3.2.4). If overscript is an <mo> element, the value of its accent attribute is used as the default value of accent for <mover>. If overscript is an embellished operator, the accent attribute of the <mo> element at its core is used as the default value. | 
