What rules govern how TV show opening credits are structured?
I've always been curious what decides if a credit is in the opening or closing credits. It seems loosely that cast (in order of today's "big name" significance), directors and financiers get the front spots, and everything else appears later. But lately I've been developing some specific curiosities about how cast members are credited on TV shows.
Opening credits seem to follow this rough outline:
Part of "opening credits" video segment
1. (optional) Major Actors
2. Show Title
3. Core Cast Actors
4. Directors
5. Producers
6. (optional) Episode Title
7. Episode Writers
Subtitles over beginning of show, after opening video
1. (Episode Title and Writers may appear here, instead)
2. 233
Special Guest Actors
I've probably missed a few things, and mis-ordered a few things. But, as I said, my main curiosity is about actor credits.
Typically, there is little indication of which characters the core cast actors play. Sometimes their name is edited to appear along with an image of the character as an indictator, but sometimes there is no indication. As I've never seen anyone credited in both the opening and closing credits, that leaves the potential for core actors to never be directly associated with their character. This seems potentially problematic; is there a reason for this? Are viewers expected to know who's who?
Guest actors sometimes are simply credited by name (and not being part of the opening video, this means they will never be associated with their character in credits). But often they are credited as "special guest as character name". This is quite helpful.
The thing I find really confusing is, sometimes the last few regular cast actors will get the guest actor treatment. I've seen opening video with "and actor as character" paired with an image of that character for an entire season. Why does this actor get special treatment?
Finally, sometimes guest actors will be credited at the front following the opening video, sometimes they'll be credited in the closing credits. Are there rules for deciding who get's credited early or late?
I've sometimes wondered if shows deliberately play with actor's name position to obfuscate plot arcs ("you won't think we're killing of this character if their actor is still in the opening credits", or "you won't expect this recurring guest if we place their name in the closing credits") and I've also wondered if there are thresholds for "people appearing in XX number or YY percentage of episodes get placed here." But it's difficult to build a good sampling base for this. And season 7 of Stargate SG-1 kinda took a shotgun to my guesses so far.
So... Are there rules? 233