It's taken 14 years, but Sandra Garratt has become a hot name in her industry, on the strength of an idea she had as a student in 1974. The idea was for a line of women's clothes to be sold in interchangeable modular units. Today her Multiples line is taking the clothing business by storm, racking up wholesale sales of roughly $50 million in 10 months. The odd part is that she is competing against a company she cofounded and left just two years ago.

When Garratt first began making her modular women's clothing in 1977, she called the line Units and sold it from a boutique she had opened in a run-down section of Dallas. The business blossomed, and in 1986 Garratt took on investors with the intent of expanding. In exchange for capital and the title of president, she gave up majority control in the newly formed Stinu (that's Units spelled backward) Corp., and found herself out of a job and a company within three months. Garratt says she was kicked out, but Stinu president Don Rhoden says she resigned in a huff. At any rate, J.C. Penney bought Stinu last year for a price Garratt estimates at between $50 and $75 million. "It was a very bitter experience," she says.

Bitter, but instructive. Soon after, Garratt linked up with Dallas manufacturer Jerell Inc., a $50-million, privately held firm that agreed to pay her a royalty on all sales of Multiples, the new name for her line.

Jerell has also invested $8 million to launch the line, adopting an unusual strategy. Because the multipurpose garments are so different from most women's clothing, division president Tommy Z. Hoffman has tried to get department stores to set up Multiples boutiques, where customers can, in effect, be educated about the concept. Similarly, he encourages the stores to place Multiples salespeople on commission, and maintains a 50-member staff to give in-store sales training and special presentations. The approach has been dramatically successful. More than 600 department stores have signed up nationwide, and Hoffman is now targeting specialty stores as well. "It's amazing," says Marshall Field's buyer Amy Kline. "It's one of the hottest things in ready-to-wear right now.'

Indeed, Multiples is so hot that Jerell has come up with another modular line, Singles. That disturbs Garratt, who gets no royalties on Singles. Then again, she says she knows of about 50 imitations of her modular look, and none of them seem to be hurting Multiples, which is expecting 1988 wholesale sales of $100 million and is now expanding to Europe and Canada. "Every day is a growth day," says Garratt, "and I think it could go on for a long time."

-- Martha E. Mangelsdorf