THE SCOPE of "Sandinista!" (Epic E3X 37037), the new three-record set by the Clash, is ambitious -- the creation of a unified world through a musical collective -- yet its purpose remains a nagging question. Like Talking Heads' recent attempt to go African with "Remain in Light," the Clash's eclectic showcase could easily have been released as a part of Folkways' Ethnic Series. Once again, the limits of rock 'n' roll are being tested, destroyed and then reinvented.

"Sandinista!" does not boil with the bravura of "London Calling," the Clash's furious and serious two-record revolt of 1980, instead, it bullies the listener with an irascible glee. Although very carefully planned, it seems like an assortment of throwaways (thereby gaining the distinction of being rock's first concept album ever made intentionally to appear thrown together).

Sandinistas are the Nicaraguan guerrillas who overthrew Anastasio Somoza, and as the title suggests the Clash still view their role as that of rebels marching off to war. (Or, as critic Greil Marcus has written, "as rock 'n' roll politicians out to create a new rock version of the public space.") Yet there's a keen difference between their first political statement in 1977 and their current mastodonic project: Now their protests are laced with a humor that defies the insularity of the punk community as it regales the outside world.

In a sense, it is this joking which detracts from the weight of the Clash's art. "Ivan Meets G. I. Joe" is a cartoon vision of World War III to a disco beat. "Hitsville U.K.," sung by women, is a silly salute to England's independent record labels. "Rebel Waltz" is a revolution in waltz time. "Mensforth Hill" offers backward tapes of inane noises; and "The Sound of the Sinners" is a gospel swipe at Dylan and the omnipresent religious apocalypse. There are more than a dozen such nerve-racking experiments, an album's worth of shenanigans.

Because it's all together, side six works as comedy -- from "Version City" (a tribute to the train metaphor within the blues tradition) to the new version of "Carter Opportunities" (sung by the two young sons of keyboard player Mickey Gallagher) to "Shepherds Delight" (Monty Python plays a looney tune).

Nevertheless, "Sandinista!" is hardly a rock 'n' roll sitcom. Although it should have been a superb single album (or at the most, an eccentric double record), its outpouring of various musical styles (calypso, jazz, soul, even mood music) permits the Clash to avoid any pigeon-holes. And if at times the band's political attitude becomes too cumbersome ("Kingston Advice," "The Equaliser"), their stylistic explorations support their sincerity: The Clash have a special boundlessness that no other modern rock band can match.

The key ingredient of "Sandinista!" is reggae, particularly dub, a term originally applied to Jamaican DJ rapping, but now meaning any alternation of an original track. Last year, the Clash successfully dabbled in dub on "Bankrobber" and "Armagideon Time," both available on "Black Market Clash" (Epic 4E 36846). But dub provides the essential link to their new work's diversity, its scattered cries of combat and holocaust. On "One More Time" and "The Crooked Beat," poverty and misery become the sound of dub. The Clash's extraordinary accomplishment is that they have defined dub as the shadowy embodiment of silent grief. Similarly, the Clash also have become enamored with rapper funk, the hysterical voice-over jive-art of such aggregations as Grandmaster Flash and Furious Five. Especially amusing is "The Magnificent Seven," a weird depiction of the urban workaholic experience ("Karlo Marx and Fredrich Engels came to the checkout at 7-11"). Like a rooster swollen with braggadocio, "Sandinista!" is filled with rapping -- "Lightning Strikes (Not Once But Twice)," the hip mumbling a la Tom Waits on "Junkie Slip" and "Broadway," the two-channel stream-of-consciousness dialogue of "If Music Could Talk."

The Clash's best new songs are an odd bunch. "Somebody Got Murdered" passionately rocks with observation that every life, even the most insignificant, is precious to someone. "Charlie Don't Surf" (inspired by "Apocalypse Now") banters against the lack of world unity, while "Let's Go Crazy" evokes carnivaltime in South America.

A cover of Eddy Grant's "Police on My Back" seems a sure hit -- wild, potent and living by night. "Washington Bullets" (not about basketball) is another contender, but the album's chief highlight is "The Call Up," an anti-militarist march. Like "London Calling," it's an eloquent anthem, a call to disarm and practice peaceful coexistence.

Even if "Sandinista!" is not a concise statement, its every shard of shrapnel has some explosive force.