I am no expert on how firm that rule is I am sorry.. However we do know that Naked short selling is being cracked down on and is a hot topic as of late... thus I can't imagine anyone would want to break the rule...
Miami posted the link to the reg-sho site...
if you lose the link you can do a simple google search of reg sho list... it is a nasdaq based site that you are looking for.. should be one of the first ones to pop up... scroll down to the bottom where you will find SPNG.
Everything I say is in my own opinion do not buy sell or hold based off what I have to say.