This question is about spatial displayed problems in a cell 1-3 problem. Would I indent the numeric passage indicators (beginning and then terminating) so they are in cell 3 like the runover of the text in the problem? And if so, would the spatial addition problem be indented to be starting in the cell 5 position?
I need to consult with other committee members to give you a full answer.
But I can start with:
BANA's "Provisional Guidance on Transcribing Mathematics in UEB" (Approved May 2019) says (in part),
For displayed mathematical expressions, use blank lines preceding and following; and indent 2 cells from the runover position of the material to which they apply. –second paragraph under 3. General format
That means the spatial addition problem in your example should have its left margin at cell 5.
Now I'm going to ask others about placement of the numeric passage indicator and terminator.
You're going to love this. ... We are not totally certain! However ...
The majority of the members of NBA's committee on UEB for Technical Materials would place the numeric passage indicator and numeric terminator around a spatial arrangement in cell 1.
But I cannot point to a particular rule or guideline to support that.
Our reasoning could be explained as follows. When you start getting into displayed material, the indentions for runovers can get up to cell 9 and further. In the interest of simplifying and staying consistent, we recommend consistently putting the indicators for a numeric passage in cell 1. [Though we are very tempted to follow Braille Formats and place the indicators for a numeric passage based on those principles.]
Last, but not least, remember the final paragraph of GTM 4.1, which says,
The line above and below spatial calculations should either be blank, or should only contain the numeric passage indicator or terminator.