Bidi and interpretation of lspace/rspace

Hello,

Just to be sure, is it correct to say that lspace/rspace interpretation 
(as leading or trailing spaces) is not made in the context of the 
element where the attributes lspace/rspace are located but in the 
context of the element around which the spaces are rendered? For 
example, I think that in these three examples, we consider the 
directionality of <msub/> (LTR) and so lspace and rspace are always 
interpreted as leading and trailing spaces respectively:

<math xmlns="http://www.w3.org/1998/Math/MathML">
<mtext>_</mtext>
<msub>
<mo lspace="1em" rspace="2em">+</mo>
<mi>E</mi>
</msub>
<mtext>_</mtext>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML">
<mtext>_</mtext>
<msub>
<mrow dir="rtl"><mo lspace="1em" rspace="2em">+</mo></mrow>
<mi>E</mi>
</msub>
<mtext>_</mtext>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML">
<mrow dir="rtl">
<mstyle lspace="1em" rspace="2em">
<mrow dir="ltr">
<mtext>_</mtext>
<msub>
<mo>+</mo>
<mi>E</mi>
</msub>
<mtext>_</mtext>
</mrow>
</mstyle>
</mrow>
</math>

-- 
Frédéric Wang.
Website <http://www.maths-informatique-jeux.com/> - Weblog 
<http://www.maths-informatique-jeux.com/blog/frederic/>