For scientific programmers, it has long been a goal to have mathematical equations in their programs displayed as they would normally write them, with superscripts and subscripts in the right places, and that sort of thing.

One early attempt was the HAL/S language, developed in the 1970s for the NASA Space Shuttle program.

An equation like this:

X = A ** 2 + B$(I) ** 2

would be displayed like this:

E       2     2
M  X = A  + B
S            I

The letters E, and S at the left margin indicated exponent and subscript lines. The line marked M was the main line. (I'm not sure if M stood for main or not.) C was used for comment lines.