Like everything else in Mathematica
the textual forms of expressions can themselves be represented as expressions. Textual forms that consist of one-dimensional sequences of characters can be represented directly as ordinary Mathematica
strings. Textual forms that involve subscripts, superscripts and other two-dimensional constructs, however, can be represented by nested collections of two-dimensional boxes.
If you use the notebook front end for Mathematica
, then you can see the expression that corresponds to the textual form of each cell by using the menu item.