For those of you who remember the late, lamented "thirtysomething," imagine that Hope, Ellyn and Melissa had moved to Pittsburgh and decided to become cops.

What you'd have is "Sirens," which premieres tonight on ABC (9 p.m., Ch. 4).And that is not a compliment.

Ann Lewis Hamilton, an Emmy-winning writer on "thirtysome-thing," created this new series about three rookie policewomen, which can't quite decide what it wants to be.

Is it a cop show?

So it sometimes appears, what with the kind of action TV types love to call "gritty" and plenty of hand-held cameras, giving it the feeling of a reality show like "COPS."

Is it a yuppie drama?

So it all-too-often appears. There's enough angst in the first couple of episodes to keep the "thirtysomething" crowd going for half a season.

Is it a soap opera?

Well, yes. Just take a look at the three lead characters.

There's Sarah (Jayne Brook), whose marriage is none to strong. She' partnered with hunky Buddy (Tim Thomerson), who's been married and divorced three times.

There's Lynn (Adrienne Joi-Johnson, the divorced mother of three. She's partnered with Dan (John Terlesky), the older father type.

And there's Holly (Liza Snyder), the gorgeous gulf war veteran who comes from a family of cops. She's partner with Heidi (Deirdre O'Connell), an ill-tempered older woman.

The behind-the-scenes drama often overshadows minor occurrences like horrible auto accidents, robbery and death.

"Sirens" isn't terrible - although it does have some terrible moments. For a show that's created and written by a woman, there are a surprising number of sexist stereotypes.

The women seem to need their male partners to protect them from sexism. When a bartender calls Lynn "sweetie," it's up to her partner to inform the guy "She's not your sweetie."

When a bad guy belts Sarah in the face, her kindly partner says, "You look kind of cute, all bloody and screwed up."

In next week's episode, one of the women even says that basketball is a man's dominion.

"Sirens" is the sort of touchy-feely, pseudo-drama that NBC has found success with on "Sisters." Like "Sisters," "Sirens" never rings particularly true.

What's most disappointing is that "Sirens" had potential. Maybe when it grows up and decides what it wants to be, it might amount to something.

Assuming, of course, that it's around long enough to grow up.

CBS's "How'd They Do That?" (7 p.m., Ch. 5) is another show that can't quite make up its mind what it wants to be.

On the one hand, it has some fascinating and entertaining segments answering the title question.

How did a couple of guys make tons of money by putting pant legs on their heads? How did Billy Ray Cyrus become an "overnight" sensation?

How do they get a pear in a bottle of pear brandy? How do they make commercials that feature killer whales swimming through an airliner and guys jumping out of a plane and "air surfing?"

Unfortunately, the mix here is uncomfortable. Try to imagine a show that mixes the guys with pant legs on their heads and a report on how investigators were able to piece together evidence about the bombing of a Pan Am jet over Lockerbie, Scotland.

And while individual segments can be interesting, amusing or both, the show is tied together sort of as an updating of "Real People." Hosts Pat O'Brien and Dorothy Lucey are energetically nauseatingly cute, spouting silly intros and lame banter.

And the addition of a studio audience is just plain dumb.

Segment by segment, "How'd They Do That?" is actually one of the more entertaining reality shows on TV.

But taken as a package, it's considerably less endearing.