The watchword for today's fifth annual KROQ Weenie Roast & Luau at Irvine Meadows Amphitheatre is "whatever."
     That's "whatever" in the good, old-fashioned sense--as in open-ended, indeterminate, teeming with choices. The biggest and potentially best Weenie Roast bill to date, this 11 1/2-hour, 19-band festival (five of them emerging Southland acts playing on a satellite stage) reflects a period of flux on the modern rock scene.
     It offers no clear focus or degree of certitude for anyone trying to peg the genre to a prevailing style or trend. Instead, the spirit of the day, if everyone plays well, could drift back to the mid-'70s infancy of the "alternative" movement, when Patti Smith rose from the underground with a mantra that threw down a challenge: "Seize the possibilities."
     Here are the various possibilities to be put forward on the main stage as the influential Southern California radio station conducts its annual orgy of self-promotion and philanthropy (the show will benefit four area charities concerned with AIDS and the environment).
     * Punk and grunge survivors. Modern rock went from an outsiders' truly alternative music in the '80s to a mainstream commercial force in the '90s as first grunge, then pop-flavored punk, captured a huge public and became the genre's signature sound. But the wave broke last year, sinking the ratings of modern rock stations, including KROQ. As the format tries to adjust--KROQ's turn toward greater diversity has improved ratings so far in '97--aggressive guitar bands like the Foo Fighters, a Nirvana offshoot, and the Offspring, who helped power the punk boom of '94-95, will try to find a lasting place in the mix.
     * Pop-rock traditionalism. Oasis, Blur, Radiohead and the Wallflowers all emphasize grabbing melody over raw power, putting them in a classic line stretching back to the 1960s.
     * Ska-influenced rock bands. Are they just the flavor of the moment, as some sated observers believe? Reel Big Fish and the Mighty Mighty Bosstones will try to show some staying power at Irvine.
     * The old guard. Through all trends, KROQ has had a soft spot for moodily brooding English rockers who play with grand, romantic sweep. Welcome back the Cure and Echo & the Bunnymen. Old-line punk warriors Social Distortion have been pummeling the airwaves at 106.7 since 1980.
     * This year's model. Is electronic dance music destined to be the pounding heart of modern rock? Never mind the hype, here are the Chemical Brothers.
     * Novelty. The Squirrel Nut Zippers' retro act looks back to the glamorous swing and vaudeville of Cab Calloway and Billie Holiday.
     "This is exactly the way KROQ sounds right now," said Gene Sandbloom, the station's assistant program director. "The trends can go in any of six or seven directions, and we're playing all of them. Personally, I'm more excited about music than in the one-dimensional period when you could identify the entire format with 10 band names."
     Such uncertainty might be nerve-racking for people charged with developing new stars or preserving the careers of recent-vintage ones. But it's not hard to find approving voices among music business veterans who also are veteran KROQ listeners.
     "This reminds me of the 1979-80 days at KROQ, when you could hear AC/DC's 'Back in Black,' 'In the Air Tonight' by Phil Collins and 'Johnny Are You Queer?' by Josie Cotton," said Mike Jacobs, a veteran alternative radio record promoter who now runs his own label, the MCA affiliate Way Cool Music.
     Sky Daniels, who covers alternative radio for the trade publication Radio & Records, said that last year was a brutal one for the modern rock format.
     "Six months ago, the ratings were down, and the panic was palpable. I was having to counsel young programmers to get them off the ledge."
     KROQ was among those hard hit. Having danced through the grunge and punk heyday of '94-95 with a 4.2% to 4.7% share of the radio market in Los Angeles and Orange counties, KROQ flopped to 2.9% at the end of '96. Daniels praises the station's new diversified approach as a way out of the post-grunge blahs and as a shrewd strategy for outflanking newer modern rock competitors in the Southern California market. KROQ's ratings rose to 3.4% for the first quarter of '97.
     "I think there's a realization by the [modern rock] format that 'We can be a thinking man's hit radio, we can appropriate a lot of genres, we can be inclusive,' " Daniels said. "You can affect a lot of what's acceptable to the market. You basically define the taste, as long as you don't push it too far."