NEW YORK (FORTUNE) - Friends, be warned: If you're hoping to find a new job through a job board or other online channel -- or if you're an employer seeking candidates on the Web -- the world just got a little bit more difficult.

New federal guidelines meant to standardize how employers track data on the diversity of their job-applicant pool are taking effect starting today for jobs at federal contractors -- and similar rules will kick in later this year at U.S. companies with more than 50 employees. And resumes and search approaches that worked perfectly well before may no longer do the trick.

In the new system, federal regulators will be checking to see that companies are keeping diversity data on all applicants, according to a new, more uniform definition of "applicant."

According to this definition, an applicant must "express interest" in the job, whether by sending in a resume, applying on the company's site, or whatever other means the company requests, says Gerry Crispin, founder and principal of CareerXRoads and a long-time Internet job hunting expert.

That "expression of interest" must show that he or she has all the qualifications for the job listed in the company's job description (not just some or most of them) -- and those qualifications must be specific and measurable.

The applicant must be considered for a specific current or future position, and "never remove himself from consideration for the job," says Crispin. For example, "if I have a job opening in Boston, for example, and you've specified that you want to work in Chicago, I can infer that you've removed yourself," he says.

To comply with these new rules and get the most diversity, employers will have an incentive to keep the pool of applicants for each job relatively small and as random as possible. To make sure you're considered now, you'll have to:

Follow the company's instructions. "If an employer says that, to apply for a given job, you must go to their web site and enter a certain code number, then do that," says Crispin. "Otherwise your resume will never be seen."

Spell out your qualifications clearly. "Pay very close attention to the specific qualifications an employer lists for a particular job, and make sure your resume contains those exact words," Crispin says.

For instance, if a job description includes the words "three years of credit accounting experience," put "three years of credit accounting experience" on your resume. "Don't just list a credit-accounting position with the dates you had it and assume someone will figure it out," Crispin advises. This may mean you have to rewrite your resume for each job opening you apply for.

Keep your resume up-to-the-minute current. "The rules allow companies to pick a random pool of applicants by searching the job boards for 'most recent' qualified applicants," Crispin notes. "In those cases, no one will even look at a resume that is more than two or three weeks old." Yikes.

Target specific companies and visit their web sites often. "The first announcement of a job opening very often appears on a company's own site before it is posted anywhere else," says Crispin. If enough applicants turn up on the site, the employer is unlikely to look any further. "Companies really do not want 500 or 1,000 applicants for each job," Crispin says. "If they get 30 who are qualified, that's a reasonable number for a hiring manager to consider and select from."

If someone is referring you for a job, make sure you -- and they -- understand how to do it. About one-third of all new hires now come through employee-referral programs, and companies are still permitted to run these however they like, as long as they follow a consistent policy. So if your pal at Ostrich Corp. wants to refer you for a job, know what Ostrich's policy is (whether via the company web site, having your friend submit your resume for you in a particular way, or what-have-you) and follow it to the letter.

Of course, it remains to be seen whether the new rules will actually increase diversity in companies or just create extra work for everybody. Either way, if you're looking for a new job, you can't afford to ignore them.

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