A friend who works for Sony shared this article today, which she said basically covers exactly what she does for her job at Sony. Noting myself that almost ALL fan films tend to botch up credits and how they are used and what they "mean" I thought I'd share here for future reference:
ASSEMBLING THE BILLING BLOCK
And while the MPAA rules don't exactly equate to or are necessarily usable with most fan films, I can tell you right now as a professional working in scripted drama TV, you lose a little bit of credibility when your credits are all over the place, inaccurate, or just nonsensical or even just plain too long. It even glances over what the difference between "A _____ film" vs "A film by ______" is (hint: one pays you more money than the other).
And yes, while the billing block is in fact a different beast than the credits of a film, this is nonetheless a great article and one that I think would be an invaluable tool for everyone to have for their reference.