Subscripts, Bars, and Other Modifiers

Here is a typical palette of modifiers.

The Wolfram Language allows you to use any expression as a subscript:

Expand[(((1+(Subscript[x, 1+n])))^4)]

Unless you specifically tell it otherwise, the Wolfram System will interpret a superscript as a power:

Factor[(Subscript[x, n]^4)-1]

Special input forms based on control characters. The second forms given should work on any keyboard.

This enters a subscript using control keys:

Expand[(1 + x Ctrl+_ 1+n Ctrl+Space )^4]

Just as Ctrl+^ and Ctrl+_ go to superscript and subscript positions, so also Ctrl+& and Ctrl+4 can be used to go to positions directly above and below. With the layout of a standard English-language keyboard Ctrl+& is directly to the right of Ctrl+^ while Ctrl+4 is directly to the right of Ctrl+_.

Ways to enter some common modifiers using control keys.

Here is (OverBar[x]):

x Ctrl+& _ Ctrl+Space

You can use (OverBar[x]) as a variable:

Solve[a^2==%,a]