For more than a decade, Diane Gartner of Atlantic Beach, NY, has kept her career in ad sales going strong. She's even stayed at the same company—ABC television. But she's changed the size and shape of her job over and over again. The short version? Diane worked full-time after the birth of her first child, stayed home after her second, then went back after her third. Last summer Diane returned to ABC for a three-month stint. She plans to work full-time in 2005. Diane's mix-and-match, in-and-out approach to work might sound a little scattered. But it's actually been deliberate—and is increasingly common. The first generation of working mothers, so focused on making inroads into various careers, was more likely to follow the straight-and-narrow company game plan. For the new wave, a career is more like a hike in the woods—with frequent detours and occasional stops at scenic overlooks. "The definition of career path has changed,'' says James Chung of Reach Associates, a marketing firm based in the Boston area. A 2003 Reach study showed that 84 percent of Gen X moms at home with children expected to return to work. Going back is just one variation on the theme: "You can have it all, just not at the same time,'' says Kathleen Christensen of the Alfred P. Sloan Foundation program on Workplace, Workforce and Working Families. Women need points of "entry, exit and reentry."Helping spur this trend is a demographic storm: Just six years from now, according to U.S. Department of Labor research reports, the oldest of the 76 million baby boomers will start to retire, which could create a historic shortage of workers. One place employers will look, say experts such as CPRi, a Chicago-based firm that places temporary marketing professionals, is to moms who want to work—but on their own terms. Some big companies are already using innovative programs (see "Working Mother Approved") to keep up relationships with "alums" who've worked for them, helping them retool and come back, says Christensen. "They don't want to lose their entire investment and allow those women to go and work for someone else.''That's good news, putting women (and men) under less pressure to conform to old standards of career growth and loyalty. "The employer-employee bond has morphed into a short-term transactional relationship," says Bruce Tulgan of RainmakerThinking, a New Haven, CT-based management firm.Still, there aren't many models to follow. Wherever you are now in your career, you probably have more than one hard decision ahead of you. But if you think strategically, it will pay off. In research for our book, Going Back to Work: A Survival Guide for Comeback Moms, my coauthor, Loretta Kaufman, and I heard many heartening stories. Here are the top eight questions we've been fielding from women—and some strategic answers.Question: I plan to leave my job to stay at home with my children for a while. How should I break the news to my boss?Answer: It's always smart to leave with a bang. So during the last six months, give your best performance. Your boss and colleagues should be sad, not glad, to see you go. If you want to stop working completely for a few years, give the company as much notice as possible. (Two weeks' notice is customary, but you can add to that if you feel that your job will be safe until the departure date you choose.)If you're interested in part-time work, you may be able to minimize the trade-off you're making. Think about any part of your current job that could be done on a contract basis and make a proposal to your boss. That approach worked well for Annette Herbert of Sussex, WI, who was a buyer for Mason Shoe, a catalog company. She stayed home for two years until her older child, Breanna, now 7, started kindergarten. Annette wanted a job she could do at home, so she called her former boss at Mason. "I knew what kind of help they could use, so I pitched a few ideas,'' she says. She now works 10 to 15 hours a week for Mason, helping vendors select products for Mason's website and performing sales analysis. "It's mutual admiration," says Annette. "I know the company, the personalities. They also know and trust me."Question: I just had my second child. I plan to be home until both kids start school. How can I avoid a big black hole on my resum