Port Adelaide has enriched Australian football with some of its grandest traditions - and a symbol that has become one of the most-admired jumpers in the game. It certainly has created the most passion ... and debate.

NO-ONE knows the true origins to the design of the guernsey that has defined the Port Adelaide Football Club for more than a century. But everyone knows it is Port Adelaide ... distinctly Port Adelaide.

Black and white. Black frame. White stripes from the base to the chest - and a white bar across the heart line that beats stronger to those who wear the jumper.

"It is a great symbol for our club and our people," says former Port Adelaide captain Tom Jonas. He speaks of how he and his team-mates would find a new sense of power in the bars jumper - and walking taller when draped with the most-enduring and traditional symbol of the Port Adelaide Football Club.

They said the same immediately in 1902 - on May 3 when the black-and-white jumper appeared for the first time in a premiership match, at Alberton Oval against North Adelaide - as the deep sentimental attachment to an old guernsey was put aside in victory.

And today's Port Adelaide players - many drawn to Alberton by the AFL's levers rather than a traditional upbringing in black-and-whites jumpers through the junior grades - appreciate the significance of a guernsey many refuse to have turned into a museum relic.

"The players love to wear it, obviously," says club Hall of Famer Robbie Gray.

History records the black-and-white bars replaced the club's magenta-and-blue stripes for the 1902 SANFL out of a practical need - "for some seasons past it has been difficult to obtain a costume which would retain the magenta dye for any length of time."

History also tells - with clouded tales of "agreements" between Port Adelaide, the AFL and Collingwood - of the demand to put aside the traditional black-and-white jumper as part of the entry conditions to the national competition in 1997.

The change to black and white in 1902 was resisted by many in the club's membership base and some old-guard players on "sentimental grounds" - and today is craved by Port Adelaide fans (and others) as the true symbol of the club's traditions, values and history that is defined by premierships.

"This magnificent black-and-white guernsey belongs to our people. It’s our people’s guernsey," says Port Adelaide president David Koch. "Our fans have asked for this guernsey. They understand more than any the importance of heritage and tradition."

There is pain for those who have failed to grasp how the Port Adelaide jumper absorbs the emotions of its people. This group included then AFL chief executive Gillon McLachlan in 2014 when his league sought to deny Port Adelaide a home jumper for its first home final at Adelaide Oval, a call that surprised even the opponent, Richmond.

"Who would have thought grown men would care what other men are wearing? But that passion is to be ignored at our peril," said McLachlan in finally comprehending why Port Adelaide people carry as much spirit as their players for a jumper that has much mystique as it has tradition.

Are those six vertical white bars and the lone vertical bar a representation of the dock pylons at the Port Adelaide wharves? Or was the bar across the chest to avoid the new jumper being seen as a direct replica of the South Australian State team guernsey worn from 1891-1905?

Those full black-and-white vertical stripes were adopted by Port Adelaide in 1923-27 and again from 1941 until 1953, on the eve of the record run of six consecutive SANFL premierships. It was at one of the premiership dinners during the 1954-1959 triumph that the world's greatest cricketer, Sir Donald Bradman (a South Adelaide football supporter), told club leader (and fellow cricketer) Bob McLean that the bars jumper was the best from then crowded Port Adelaide wardrobe.

So many others from so many different quarters of Australian football have agreed, particularly through the protracted dispute to give Port Adelaide the appropriate match-day space in the AFL to honour a tradition that is as so strong as the New York Yankees wearing blue pinstripes in Major League Baseball.

Today, Port Adelaide wears the black-and-white bars in home Showdowns at Adelaide Oval. The derby reflects how Port Adelaide - in black and white - set itself apart from the rest in South Australian football to live the "them against us" mantra established under patriarch Fos Williams.

It is a jumper that carries great power built on a century of tradition - and even greater responsibility to those, as Jonas notes, earns the "privilege" to wear the bars guernsey. The living theme of the jumper is recalled by Magarey Medallist Peter Woite on his handover of the No.17 guernsey at Alberton by premiership hero Geof Motley during the 1960s.

"Geof shook my hand," recalls Woite, "and he said, 'Son, the player makes the jumper; the jumper does not make the player. Remember that'."

In seeking a traditional moment - in particular the Showdown - as the AFL showpiece for the bars guernsey, Port Adelaide has ensured the heritage of its club and South Australian football is not forgotten. It lives on with special meaning. To players, to fans, to a proud club and to the game itself.