Doesn't rule #3 make rule #5 redundant? If package variables can already be identified by their being in all caps, pretty much anything else you run across is therefore by definition local to that subroutine, isn't it? Besides, I can't help but feel that after a while all the this_ and local_ are going to drive you absolutely nuts. Variables being local to subroutines should be the rule, not the exception, so in my opinion perhaps it would be better if the variables that aren't local get their own little prefix :-)