In the long division example in 3.6.8.3, the line
<mn> 1.0</mn>
should not be inside the msgroup with position='-1'. The decimal point essentially changes the alignment some, and in this case, it should have position='0'. To do this, it should move up into the previous msgroup.
Here's what I think it should be:
<mlongdiv longdivstyle="stackedrightright">
<mn> 435.3</mn>
<mn> 3 </mn>
<mn> 1306</mn>
<msgroup position="2" shift="-1">
<msgroup>
<mn> 12</mn>
<msline length="2"/>
</msgroup>
<msgroup>
<mn> 10</mn>
<mn> 9</mn>
<msline length="2"/>
</msgroup>
<msgroup>
<mn> 16</mn>
<mn> 15</mn>
<msline length="2"/>
<mn> 1.0</mn> <!-- the '.' preserves alignment of 1.0 as opposed to '10'-->
</msgroup>
<msgroup position='-1'> <!-- extra shift to move to the right of the "." -->
<mn> 9</mn>
<msline length="3"/>
<mn> 1</mn>
</msgroup>
</msgroup>
</mlongdiv>