Film and TV writers walked away from their computer keyboards and joined picket lines on Monday after their demands for a bigger piece of Internet-derived revenues were not met.

Picket lines began to appear outside NBC headquarters in New York's Rockefeller Center early, while in Los Angeles, writers were planning to picket 14 studio locations in four-hour shifts each day until a new deal is reached.

The contract between the 12,000-member Writers Guild of America and the Alliance of Motion Picture and Television Producer expired Oct. 31. Talks that began this summer failed to produce much progress on the writers' key demand for a bigger slice of revenues from the distribution of films and TV shows over the Internet.

It is the first strike since 1988.

On Friday night, the cast and crew on the television show The Sarah Connor Chronicles, which is set to begin airing in January on Fox, had taken over part of a Los Angeles park. They were filming a scene involving the search for a corpse in a ravine.

Thomas Dekker plays John Connor, son of Sarah. At 19, he's already a veteran actor. And he's ready to take the strike in stride.

"It does threaten everything, but it's for a cause that I understand, and I respect it and hope it goes away soon," Connor said.

James Middleton is a producer on the show. Even before the picketing, he said, the strike was causing disruption.

"It creates tension and anxiety throughout the crew. Because first there's uncertainty and that makes everyone nervous and it takes your focus away from the task at hand," Middleton said.

As for writing the show, that's Josh Friedman's job. And Middleton says if Friedman can't write, production will grind to a halt.

"It's horrible, I mean he's my friend and the writing staff becomes your family. There's 10 people that are on our writing staff from staff writers up to our show-runner," Middleton said.

A show-runner is usually a producer and a writer—a person who wears two hats. Show runners make the most money, and they are in a delicate position. Contractually, they are obligated to do their producing jobs. But it is not clear where producing ends and writing begins.

"There are grey areas in terms of is something a producing function or is something a writing function," said Daniel Black, an attorney who represents a number of show-runners.

Black's clients are in a quandary. For example, the Writers Guild is ordering them to turn over copies of all scripts so the union can figure out whether changes have been made during the strike and punish the offenders. But the studios and networks are warning them not to provide the material. There are also day-to-day issues that arise during filming. If dialogue isn't working, can a producer-writer tweak the scene without violating strike rules?

"I think decisions are going to be made on the set and whether it's writing or not, everyone is going to try to do what they can … to complete the scene," Black said.

That may be optimistic. Last week, dozens of show runners signed an ad in the trade paper Variety. They warned that they would enforce the strike vigorously. They come from programs as diverse at 30 Rock, Desperate Housewives, Hannah Montana, Grey's Anatomy and Ugly Betty.

On the set of the Sarah Connor Chronicles, James Middleton says it might be possible to work through scripts that have already been written. But he is worried that won't be enough.

Middleton and every other producer want a chance for their show to build an audience. But the networks could use a prolonged strike as an opportunity to drop a show if the early ratings are short of spectacular.

The two sides met for nearly 11 hours before East Coast members of the writers union announced on their Web site that the strike had begun for their 4,000 members.

"It is unfortunate that they choose to take this irresponsible action," producers said in a statement.

With additional reporting from The Associated Press