The function is producing a chunk with subscript vertical alignment.
It is used to add it to the content of a cell of the
flextable with the functions compose(), append_chunks()
or prepend_chunks().
See also
Other chunk elements for paragraph:
as_b(),
as_bracket(),
as_chunk(),
as_equation(),
as_highlight(),
as_i(),
as_image(),
as_sup(),
as_word_field(),
colorize(),
gg_chunk(),
grid_chunk(),
hyperlink_text(),
linerange(),
minibar(),
plot_chunk()
