I think it is right to use single-letters as locals. I belive that the best programming style is to always use short (50 lines max) and simple functions with no more than 7 locals. (Compare linux coding convention.) This way, it is no probem to use single-letter variables, as each function does only one thing so it is easy to understand and see how it works and what each variable does. (This is more true to C then Perl of course.)