This question maybe a little tiny.
Firstly, let's input underscript Ctrl+4 in an inline cell.
InlineFormula
inline cell $\underset{n\to\infty}{\text{li}}$
However, if we use $\lim$, we get $\lim_{n\to \infty }$ .
Note: it looks the same in my Notebook
as Subscript
by Ctrl+- $\lim _{n\to \infty }$
TextStyleCell with InlineFormula Inline cells:
For clarity, here's the Cell expression:
cellExpression = Cell[
TextData[{
"subscript: ",
Cell[BoxData[SubscriptBox["lim",RowBox[{"n","->","\[Infinity]"}]]],"InlineFormula"],
" underscript: ",
Cell[BoxData[UnderscriptBox["lim",RowBox[{"n","->","\[Infinity]"}]]],"InlineFormula"]
}],
"Text"
];
and this is what it looks like in my notebook:
CellPrint[cellExpression]
So how to show $\underset{n\to\infty}{\text{lim}}$ in Notebook's InlineFormula
cell?
Further, you'll see that when exported to TeX, they are same.
StringCases[
ExportString[cellExpression,"TeX"],
"\\begin{document}"~~x__~~"\\end{document}" :> StringTrim@x
]
(*
{subscript: \(\lim _{n\text{-$>$}\infty }\) underscript: \(\lim_{n\text{-$>$}\infty }\)}
*)