One-letter abbreviations

These are highly context-dependent in their meaning, but in general:

Letter	Meaning(s)
`a`	Accumulator, generic first variable in sequence
`b`	See `a` above
`c`	Current value, see `a` above
`d`	Difference, delta
`e`	Expression, exception, error, event
`f`	File, function
`g`	Also a function
`i`	Index, iterator, imaginary
`j`	Also an index, also imaginary
`l`	Length, list, long, last
`n`	Number
`o`	Object, out
`p`	Pointer
`r`	Return value, result
`s`	Size
`t`	Time, period
`v`	Vector, variable
`x`	First field of a vector, generic first variable in sequence, literally anything else
`y`	Second field of a vector, see `x` above
`z`	Third field of a vector, see `x` above, complex number