Fashion comes unbuttoned: How low will it go?

The stylish shrinkage of men's suiting has had its fashion repercussions. Pants are straighter. Shirts are tighter. Ties are fewer.

And as more men go tieless — whether dining out or meeting with corporate colleagues — they are deciding to leave more of those top buttons open. What hasn't been determined, though, is where the unbuttoning stops.

"Buttoned all the way to the top is just nerdy, the second button is uptight, and the fourth button is all playboy," said Craig Arthur von Schroeder, 31, a construction law attorney behind fledgling fitted-shirt company Commonwealth Proper.

"It should definitely be the third button."

In men's fashion circles, the debate is brewing as to where the tieless man should button his button-down.

What's certain: Under no circumstances should undershirts show. (It's all about the deep V for today's trendy man.) Otherwise, the race to be the top buttoned button remains at a dead heat between the second and the third. To make the decision easier, shirt makers are taking matters into their own hands.

On certain shirts, some manufacturers are coloring second and third buttons to subtly let men know which ones should be closed — turning style advice into trademark territory.

Commonwealth Proper is stitching its third buttonhole navy — or what is called Commonwealth blue — to let wearers know the power is in the third button. The shirt brand Steven Alan marks the second button's backing with a different material. And the Just a Cheap Shirt label makes its second button a snap. Other companies make the second button a little higher or lower in relation to the first button to make it stand out. You'd think the button had become the next pair of Louboutins, with their trademark red bottoms.

So what's a guy to do? It depends on who you talk to. And even then, there's some wavering.

"It's between the third button and the second button," said Jon Segal, owner of Pants in Bryn Mawr, Pa. "But I would say that the second button tends to win. But then again it really depends on where the button falls."

"Top button is for the tie only," said Steve Ward, 28, self-proclaimed fashion plate and host of Tough Love on VH1. "The second button is for friends, family, maybe even business occasions. Think upscale formal atmosphere. The third button only if you are out socializing and if you are not exposing a swath of chest hair."

Some might argue the chest-baring — like daring not to wear pantyhose — is a form of disrespect. Les Schwartzberg of Center City Philadelphia boutique Les Richards argues that men don't look finished without ties and buttoned-up shirts.

"I think it's an age factor," Schwartzberg said. "I think the younger you are, the less buttons you will keep open. Businessmen are going to keep one button undone."

Yet the slimmer shirt and tieless neck have been favored by many businessmen, albeit on the younger side, who are rejecting the boxy suits and oversized tucked-in shirts of their forefathers. After all, isn't that the uniform of the old-school Wall Streeters responsible for today's collapsed economy?

And then there's President Obama, the country's top businessman, who has taken some fashion heat for wearing his Hart Schaffner Marx suits sans tie in the Oval Office or out on dates with the first lady.

It seems the key to getting away with the tieless, unbuttoned look is in the style of the suits. Shirt designer von Schroeder says the Thom Browne-esque European-style fitted suits are much neater than the boxy look, with or without a tie. That means even without a tie, the casual look can look dressy. And men are just as interested as women in wearing figure-friendly clothing.

"I like my shirts to be slim and tight," says Jesse "Schooly D" Weaver of Gladwyne, Pa. "I hate seeing grown men wearing oversized shirts that don't fit, whether they are from J.C. Penney or Donald Trump."

It's this sentiment that led von Schroeder to turn his loft in Philadelphia's Northern Liberties neighborhood into a shirt showroom this year. That, and his colleagues were looking way too messy.

"The worst thing about shirts these days is the excess fabric," von Schroeder said as he swirled black coffee in a wineglass as if it were a morning merlot. "Most guys are reasonably in shape, and they don't need a shirt where the fabric reaches down to their knees."

His shirts have a stiff collar and adjustable cuffs and buttons that show off contrasting lining. Ranging in price from $105 to $250, the shirts are available at www.commonwealthproper.com. But von Schroeder, who chose the name Commonwealth to pay homage to his home base, hopes the shirts eventually will be made in Philly.

All told, I'm a fan of the fitted, tieless look. And buttonwise? The lower you go, the better. My advice: Start at the third button and work your way down.