Mark Zuckerberg has been criticised for wearing a hoodie to a major business presentation. But should this be a problem?
People probably think they know what business people wear on business. For the women, dark suits. For the men, dark suits. Ties.
Occasional flamboyance is allowed in certain sectors. Finance whizz-kids in the 1980s took to wearing red braces.
But the code is normally formal.
These are not the rules that billionaire and Facebook founder Mark Zuckerberg subscribes to.
This week he was criticised for wearing a black hooded top to presentations to talk up Facebook's floatation, its first major sale of shares.
"Mark and his signature hoodie: He's actually showing investors he doesn't care that much; he's going to be him," analyst Michael Pachter told Bloomberg TV . "I think that's a mark of immaturity."
There have been plenty of pundits rushing to his defence . They have noted that with the floatation potentially valuing Facebook as high as $100bn (£62bn), Zuckerberg must have been concentrating on something other than dressing snappily.
So in the world of tech start-ups, can people dress however they like?
Richard Anton, partner at technology venture capital firm Amadeus and former chairman of the British Private Equity and Venture Capital Association, encounters many entrepreneurs in "jeans, T-shirt, ponytail".
"We have had people wearing sandals," he notes.
But the key thing is the business.
"The people we back are always visionaries - really hard working, very switched on.
"The last entrepreneur I backed always wears jeans and a T-shirt to meetings. The previous one wears a suit and tie."
And the defenders of Zuckerberg have noted there is method behind his scruffy dress. His trademark black hoodie is in fact a piece of Facebook merchandise. It displays in grey the three logos for "friend requests", "messages" and "notifications".
He's also been photographed a number of times wearing a similarly logoed grey T-shirt.
And Steve Jobs is a source of inspiration.
Although he initially wore a variety of outfits including suits, a Jobs product launch came to be associated with his trademark black roll-neck jumper, blue jeans and white trainers.
Some even called the look "iconic".
It could be argued Zuckerberg is doing the same with the black hoodie.
"In a sense his hoodie is part of his personal brand and that is part of Facebook's brand. A lot of users know who he is," says Esquire editor Alex Bilmes.
"Steve Jobs didn't wear a suit. He wore the black roll-neck and terrible dad jeans and awful tennis shoes. That didn't stop him being possibly the great business brain and entrepreneur of our time."
It might even be reassuring for investors that Zuckerberg stays true to his roots as a creator, rather than appearing like every other suited business person.
"Creatives are often forgiven for their lackadaisical dress. If you are a mad genius you don't have time to worry about matching your tie in the morning," says Bilmes.
And a sense of difference, in dress as much of anything else, can be a part of the unique ethos of successful companies.
"With really powerful firms they build a cultural identity where you have a corporate ethos," says Anton. "People generally feel they are part of a team. They feel they have a shared mission, a sense of purpose.
"Dress can be part of that. There is a rebelliousness. In these tech start-ups people are often in their 20s."
Zuckerberg does occasionally don formal dress. Visits to the Japanese prime minister and the French president were both rare dark-suit occasions for the billionaire.
While arguing that Zuckerberg should not be criticised for his scruffy look, Bilmes says he might consider more formal days for purely aesthetic reasons.
"He would look a lot better if he wore a beautiful suit."