Baseball has become the first major pro league in North America to issue dress guidelines for media members, putting them in writing at the winter meetings.

Starting next season, the no-wear list includes visible undergarments, muscle shirts or anything with a team logo.

"This is not in response to any single incident," MLB spokesman Pat Courtney said Tuesday.

However, baseball was aware of the flap caused in the National Football League when a Mexican TV reporter drew unwanted attention at the New York Jets' training camp in September 2010, and formed a committee of executives and media representatives to work on guidelines.

The panel included female and Latin reporters and there was input from team trainers, who had health concerns about flip-flops in clubhouses and bare feet possibly spreading infections. Such footwear is no longer permitted.

The media should dress "in an appropriate and professional manner" with clothing proper for a "business casual work environment" when in locker rooms, dugouts, press boxes and on the field, the new MLB rules say.

Banned are sheer and see-through clothing, tank tops, one-shouldered or strapless shirts, ripped jeans or clothing exposing bare midriffs. Also listed in the guidelines are excessively short skirts, dresses or shorts cut more than 3-4 inches above the knee.

The NFL, NBA and NHL do not have similar policies.

MLB and members of the Baseball Writers' Association of America who regularly cover the sport agree that most reporters are within the boundaries. Probably not everyone, though.

"Personally, I believe the baseball media in general could dress slightly more professionally," said San Francisco Chronicle writer Susan Slusser, recently elected vice president of the BBWAA. "I think it's been a little too casual."

MLB said it would consider appropriate actions if the guidelines were broken.

At 81, former Marlins manager Jack McKeon has seen dress codes change a lot during more than a half-century in the game. Especially at warm-weather ballparks during the hottest summer months.

"I remember the old days, when even the people in Triple-A would wear a coat and tie," he said. "Now, it's casual. Less than casual, really," he said.

"Today, it can look pretty sloppy," he said. "But that's not just baseball. It's generational."