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Spring fashion is beginning to take shape in the opening days of New York Fashion Week — however loose that shape may be.

Flirty frocks are mostly short with swinging hems. Eyelet fabrics embrace the season's lighthearted spirit, while the favorite colors are black and white with pops of brights instead of traditional warm-weather pastels.

Click here for FOXNews.com's photo essay of images from the runways

However, scores of designers have yet to preview their lines before the shows wind up Friday, so there's room for other trends to show up on the catwalks.

Oscar de la Renta: De la Renta is a favorite of first ladies past and present, and for spring 2007, he seemed to have Jacqueline Kennedy on his mind.

The shift dresses and portrait-collar skirt suits seen in his show Monday were shapes rooted in the early 1960s, yet de la Renta kept them modern with interesting fabrics and embroidery. One recurring print was a Georgia O'Keeffe-style floral, sometimes in bright red, other times in bright blue.

It could have been a coincidence that the first few outfits on the runway were in red, white and blue, but in his notes, de la Renta acknowledged that his show was taking place on the fifth anniversary of the Sept. 11 terror attacks.

"Five years ago today, as I was preparing for the opening of the spring show, tragedy struck us all. Today, we honor the memory of those who died. As I present this collection, I still strongly believe in the spirit of America and the great generosity of its people," he wrote.

Embroidery is de la Renta's signature — and he didn't disappoint. A navy-and-white embroidered dress, a yellow embroidered ballgown and a form-fitting, cream-colored embroidered-lace gown had that de la Renta touch.

Bubble skirts are another de la Renta hallmark, but he probably should have skipped them this time; they were too pouffy, too dramatic and seemed out of place.

Carolina Herrera: For a designer who wrote in her notes to ignore the trends and dress for personal pleasure, Herrera hit many spring themes head on — but with a difference. Her trench coat — a feminine one in a black-and-white floral — captured the mood for next spring yet would be just as lovely many years down the road. And she freshened up toile by inserting tiny faces of Marilyn Monroe into the usually stately print.

A short shift in a red-and-white hydrangea jacquard fabric could be worn anywhere and anytime, and a beige eyelet strapless sundress with a hint of metallic shine could be the "go-to" dress of the season because of its flexibility, wearability and elegance. Herrera also included a series of dresses made from rows of embroidered ribbons in a triangular pattern that was completely unique.

Cynthia Steffe: Steffe said this collection was inspired by the scene at St. Tropez, France, and the cast of characters it draws, and tanned bathing beauties would look great in her breezy white shifts. But the beautiful color blue she used for many of her cocktail dresses looked more like the nearby Mediterranean. One look that bridged the beach was a blue eyelet halter dress.

Jill Stuart: Stuart knows her customer — young women who are comfortable wearing very little and who have such shapely figures that their clothes don't need much structure. For these customers, there were lots of options, including swinging minidresses in layers of lace. The best ones were a rose-colored lace baby-doll dress and a white strapless dress with a nude-colored lace overlay shift over it.

Click here for FOXNews.com's photo essay of images from the runways