Copy Marking
It is essential to mark carefully each character, letter, and symbol that may be mistaken for another form (eg, x, X, χ2, ×2, 2x, x2).
The following examples show correct markup for complex relations between elements of equations:
In expressions that involve both superscripts and subscripts, the subscript is usually aligned directly under the superscript. In online publication, this alignment can generally be created only by using an image.