Using the 'l' to denote local scope is somewhat redundant since in well-written code almost everything is local. We ditched the 'l'/'t' some five years ago and changed the few non-locals that exist by special permit to have an additional underscore to make them stick out like sore thumbs (g_oApp, p_nFoo); single-letter variables are exempt from prefixing but required to be local. This makes the code a lot easier to read (unless you are used to the 'l' prefix and seeing a lot of variables without it makes you feel queasy).

More important than 'l' vs. not 'l' is to qualify references to memory variables with m. wherever necessary but many Fox coding standards are conspicuously silent on this issue and many people only wake up (a little) when they get bitten by the problem.