Like Gaul ("Divisa in tres partes"), New York theater is divided into Broadway, Off-Broadway and Off-Off-Broadway.

Broadway, of course, is hit territory, where the jackpot can strike in one night -- or, as happened with the music-less "Frankenstein," $2 million goes down the drain in two hours, with dilettante backers writing off their mindless gamble as a tax loss.

Off-Broadway, has become a real-estate market, rentals and percentages rising so that owners of dumpy old properties skim the cream before writers and artists can sip the milk.

Off-Off-Broadway is "Showcase" territory, where iffy plays and untried playwrights once had a chance for an audience, the only possible rewards to be had through future productions.

But Off-Off-Broadway has been drying up, and instead of new works you're more likely to run into meager revivals of authors long enough gone to make royalty payments unnecessary. The problem has existed for 17 months, since Actors Equity declared that its members involved in "showcase" productions be guaranteed a cut in a work's future versions. This means that unless the Equity member is given his same role, the future producers will have to pay some of their production costs to the original performers.

Though executive secretary Donald Grody has since been relieved of his post, the Equity ruling still holds, with the result that Off-Off-Broadway is in sharp creative decline.

Such Off-Off graduate playwrights as Michael Wellers, David Mamet and Romulus Linney -- backed by the Dramatists Guild -- have sued Equity under the Sherman Anti-Trust and National Labor Relations Acts. But because they respect Equity's members as their creative interpreters, the dramatists have tackled the delicate impasse with publicly controlled caution.

The Guild's battle is being waged from a historic site, the longtime apartment of the late J.J. Shubert, in an upper floor of the Sardi Building, facing the Shubert Theater, where J.J.'s late brother and partner, Lee, had his apartment. The constantly warring brother spoke to one another only through intermediaries but it wasn't impossible to spy on one another.

Though now surrounded by files, desks, Xerox machines and other impedimenta of strictly business operations, the Guild's conference room maintains the baronial splendor to which J.J., one of the three "Boys From Syracuse," accustomed himself. It's a marble room with an 18-foot ceiling, a fireplace suitale for roasting mastodons and a carved brass door so enormous and heavy that the dramatists use it not for entrances and exists but purely for decoration. "You'd need to tear down the building to get the thing out," said one who's clearly given some thought to its worth as scrap metal.

In this conference room, where J.J. once chased chorus girls around sofas and tables in the wee morning hours, the dramatists have been plotting negotiations as delicate as those with a Shiite iman.

Dramatists Guild executive secretary David Levine is in a hopeful frame of mind, for new-play production also has been way down in the usually lively Los Angeles area. "It now may be a matter of timing" is his most recent, cautious comment.

On the other side, Equity's acting executive secretary, Willard Swire (unlike Grody, a longtime theatrical insider), is known to be making conciliatory gestures and is fully aware that all acting jobs from playwrights flow.

Were the New Playwrights's Theatre of Washington able to afford Equity conditions, it too might find its search for new playwrights curtailed. As it is, life goes on on Church Street, where Tim Grundmann's "Dear Desparate" recently began its hopeful career.

Off-Broadway also has suffered a sorry loss: the collapse of Robert Kalfin's Chelsea Theatre Center. Born in Brooklyn 16 years ago, the Chelsea has had a truly distinguished career -- last season's "Strider" was strong on the Tony listings and Hal Prince's reworked "Candide" got its start in that organization.

The irony here is that Kalfin has paid off Chelsea's entire deficit, but has no funds to continue. This season's opener, "Hijinks," a musical inspired by Clyde Fitch's 80-year-old comedy, "Captain Jinks of the Horse Marines," got respectable notices but payment of debt leaves the treasury empty.

It's a long, complex story, which Kalfin sums up as "changed ground rules."

The emphasis on grant funding, governmental and otherwise, he says, "has shifted to the number of performances and the number of people you are reaching. We have become dependent on subscription sales to prove things, pushing one to make safe choices. I can't do that, never have.The nonprofit theater began as an alternative to commercial theater. Now the rules have been switched to commercial success.

"Funding sources get bored with established groups and go searching for new ones. We're burning out our mature groups and artists in this way. We keep having to reinvent the wheel."

Having run and directed one of the country's most stimulating theaters during the prime years of his life, Kalfin now admits he's looking for a job.

That trend Kalfin notes toward playing it safe could become a slow poison for the whole regional theater network -- including Washington's Arena Stage. Because it has been around twice as long as the Chelsea is no reason to assume that Arena automatically will survive forever. This is a decidedly worrisome black cloud on the horizon. The only good thing about the Chelsea's demise is that it frees the dynamic kalfin to stretch for broader horizons.