// An inset for super- and subscripts or both. The 'nucleus' is always
// cell 0. If there is just one script, it's cell 1 and cell_1_is_up_
// is set accordingly. If both are used, cell 1 is up and cell 2 is down.
// An inset for super- and subscripts or both. The 'nucleus' is always
// cell 0. If there is just one script, it's cell 1 and cell_1_is_up_
// is set accordingly. If both are used, cell 1 is up and cell 2 is down.