OS ANGELES - Until almost the moment the stars step onto the red carpet, Patsy Burns expects to be working on her Oscar outfit.
She knows it should be elegant. She'd like it to be silky and satiny and feathery, too. She's thinking a dress you'd wear to watch the Titanic sink or sweep the Academy Awards on television tomorrow night.
''We always dress like what we think is going to win Best Picture,'' said Burns, a retired kindergarten teacher who grew up under the Hollywood sign and will be watching the Oscar ceremonies on TV with friends. ''I have never missed an Oscars, even when I was growing up and the awards were only on radio. In fact, my interest has become more intense over time.''
Like much of Los Angeles, Burns is swept up each year in Oscar insanity and inanity. It begins with the nominations, then starts early on Oscar night, since the show begins before the sun sets on the West Coast.
Almost as much as the Jewish High Holy Days, Christmas or New Year's, the Academy Awards clear out the city's office buildings and movie studios, which virtually shut down at midday in anticipation of the annual event that matters most to them. The people with parties to attend - and there are hundreds of them around the city, from gatherings of 10 in homes to benefits for 1,000 at hotels - sneak out early, too. Otherwise they risk being stuck among wall-to-wall limousines, which will carry celebrities to the Shrine Auditorium and can back up downtown traffic for hours.
''It's kind of like a holiday in the movie business, with nobody really going to work and then partying all night,'' said John Davis, a producer whose movie credits include ''The Firm,'' ''Courage Under Fire,'' and ''Grumpy Old Men.'' ''You go to the Oscars if you're nominated; otherwise you watch at one of the parties, going from party to party to party. It's like Halloween for grownups.''
After 18 straight Oscar nights in Los Angeles, Davis is skipping this year, opting instead to take his children out of town on vacation. But Sherry Bebitch Jeffe, whose annual at-home bash is a must for Burns and 50 others, wouldn't think of being anywhere but near a TV starting at 6 p.m. sharp (9 p.m. Eastern Time on ABC). Still, Jeffe insisted the party is about more than sniping over evening gowns and hairdos gone awry, or even applauding winning films and stars popular with the crowd.
''I use this as my one night a year to see people I sometimes don't see the rest of the year,'' said Jeffe, who hands out a prize to the person who picks the most winners in advance, with balloting allowed by fax or phone. ''And it really is so L. A., so it works. We don't have a Christmas party. We don't have a Hanukkah party. We don't have a Halloween party. We have an Oscar party.''
The parties - hosted by everyone from individuals like Jeffe to Vanity Fair magazine to the Academy of Motion Picture Arts and Sciences itself - are an industry unto themselves. Valet parkers, caterers, florists and manicurists, among others, all make Oscar money day and night.
Jack Kyser, chief economist at the Economic Development Corp. of Los Angeles, estimated that the city stands to reap as much as $70 million from this year's awards, an estimate that includes satellite TV linkups for overseas broadcasters as well as designer dress sales.
''I'm an economist, so I like to see dollar signs - much more exciting to me than seeing stars,'' said Kyser, who plans to watch the Oscars from the comfort of his home. ''It's not a comfortable ceremony to go to anyway. You have to be there so early and then sit down the whole time.''
The ceremonies themselves, of course, are open to a relatively select few. The bleachers erected outside the auditorium are a more egalitarian spot from which to stargaze. Anyone can sit there - anyone lucky enough to win one of the coveted 1,000 seats.
Normally, Oscar devotees start lining up as much as six days in advance, camping out in hopes of landing a seat. This year, however, the academy tried a new system aimed at taming the star-hungry hordes. Last week, it handed out free passes to the first 500 people in line, and it will allow another 500 in today after the first group is seated.
Ric Robertson, the academy's executive administrator, has received ''plenty of gripes'' about the new system. ''One was that people really love to be living on the street for five days in anticipation of the Oscars,'' said Robertson, who plans to attend the party known as the Governor's Ball before ''going home and collapsing.''
Said Oscar Arslanian, a publicist who got inside twice for the Oscars, first in 1969, then again two years ago: ''It's great to be there not only as a spectator but to be actually going in. ... Oscar night is really something in L. A. There are no caterers available, no limos available, the hair and makeup artists are totally exhausted.''
Not surprisingly, one of the must-attend parties this year is hosted by 20th Century Fox in honor of ''Titanic,'' a Best Picture nominee. It's being held in Beverly Hills, and so many guests are expected that part of the street will be closed to traffic - a move that required City Council approval.
For his annual fund-raiser at the other end of the block, pop singer Elton John did not request any shutdown, although he did require valet parking privileges, said Beverly Hills transportation programs manager Michael Cantor. A half-dozen other residents requested valet parking for Oscar night, although the Beverly Hills Hotel has enough private parking to accommodate guests at the party it is throwing.
''Some people have the Super Bowl, and we have the Oscars,'' said Geri Wilson, marketing director at the Hollywood Entertainment Museum, which is holding a fund-raiser that more than 600 people are expected to attend, with a table for six in the ''Cheers'' bar going for $1,000. ''It's going to be very glitzy, very Hollywood. The people who come are the ones who just missed out on getting an invitation to the Governor's Ball or one of the other hot tickets.''
Aspiring actor John Casserly didn't get any of those invites this year. So he decided to throw his own party for 30 people, half of them involved in the movie industry, half of them hoping to be. With an oversized TV and the promise of prizes, he expects few no-shows.
''It might be kind of hard to have one of these parties in, say, Middle America, because the interest probably isn't there,'' said Casserly, who is originally from the Chicago suburbs. ''But I'm very interested in it, and so are most of the people I know. The Oscars might be one giant, self-congratulatory pompous event, but I wouldn't miss it for the world.''
