The inexorable countdown to a new century is under way. For most of us, of course, it’ll be a once-in-a-lifetime experience. So get ready. We have just four years to go. Or is it five years?

And therein lies the problem.

This forthcoming century, not to mention the millenium it will usher in, already is fraught with argument, and may well get under way without any agreement on just when it should begin.

In the waning years of this century, it is left to journalists, the foot soldiers for historians, to wrestle with the pressing question: Do we bid farewell to the 20th century at midnight, Dec. 31, 1999? Or do we wait a year?

That’s because centennial scholars are divided. Some argue that since there never was a year 0, all centuries must begin at the year 1. If these experts are correct, then in the most immediate case the 21st century would begin in 2001.

Other experts, however, insist that centuries begin when the centennial digits change, such as 100, 200 and so forth. These scholars argue, with some persuasion, that the 11th century, for example, began in the year 1000.

Not too many records exist from that century, or from the ninth or 10th or 12th, for that matter, about when, exactly, people back then considered each of them to have gotten under way.

But here is some help on the subject from more recent times. And what better authority to consult than the venerable New York Times? The newspaper of record, in an editorial on Dec. 31, 1899, noted, “Tomorrow we enter upon the last year of a century.”

Sounds simple enough. The policy of The New York Times back then was, the 20th century would begin in 1901.

What a difference 96 years make. Now, according to the keepers of editorial style at the Times, the newspaper will follow “popular acceptance,” and will consider the start of the 21st century to be after the close of all business on Dec. 31, 1999.

So take that, you sticklers who want to make everyone wait a year. There’ll be no delay for the start of the new century as far as The New York Times is concerned.

The Bangor Daily News, however, is taking a more neutral position on the Centennial Controversy. Executive Editor Robert Kelleter observed, “On the news side, we don’t make policy, we cover it.”

Now to another, equally perplexing question: For those of us who want to address the new century’s years by name, how are we supposed to refer to them?

Back in 1968, Arthur C. Clarke and Stanley Kubrick inadvertently began this debate with their screenplay, “2001.” While no character in the movie ever referred to that year by name, just about everyone who has seen it has pronounced the title “Two thousand and one.”

But should Clarke and Kubrick be the arbiters on something as, well, cosmic as this?

In a little over four years, do we begin referring to our place in the calendar as the year Two Thousand? Or will we continue tradition and call it Twenty Hundred? And a couple years hence, will it be Twenty Oh-two?

After all, for the next few hours, the current year, spelled out, is Ninteen Ninety-five. It’s not One Thousand Nine Hundred and Ninety-five.

And how about past centuries? If advocates of the “Two Thousand” school of thought prevail, do we revise history?

Will we have to begin referring to our war of independence as the Revolution of One Thousand Seven Hundred and Seventy-six? Or how about that book on the history of England? Will it now be called “One Thousand and Sixty-six and All That”?

And pity concert announcers everywhere if they have to start referring to Tchaikovsky’s symphony as the “One Thousand Eight Hundred and Twelve Overture.”

This should not be of idle concern, and these are not idle questions. They affect all of us, and they should prompt centurial debate.

And, possibly, two centennial celebrations, 12 months apart, with 12 months of argument over how to refer to the new years. It promises to be quite a party.

Sandor M. Polster of Durham was for 20 years a news editor and producer for CBS Evening News and, later, NBC Nightly News. He also was a newspaper reporter.