Hereinafter, the word ''hereinafter'' is off limits. Same goes for ''hereby,'' ''whatsoever'' and ''to wit.''

There's a quiet revolution in the writing of the federal government, a crusade occurring one sentence at a time.Federal workers have been told that their usual gobbledygook is no longer acceptable. It's time to write clearly.

They're supposed to avoid the jargon and acronyms that make many government memos look like a bowl of Alpha-Bits cereal. The government has compiled a list of forbidden words and lots of tips on avoiding legalese.

Federal workers have been told to personalize their writing, to refer to the subject of their message as ''you'' and the government as the royal ''We.''

Federal employees have been instructed to stop writing long, complicated sentences that do somersaults before they get to a verb. Instead, they're supposed to write short, simple sentences and rely heavily on questions and answers.

(Q. Why use the question-and-answer format? A. Because it helps people understand complicated things.)

The effort is being pushed by President Clinton and Vice President Al Gore, but the biggest crusader is Annetta Cheek, a veteran bureaucrat at the U.S. Bureau of Land Management.

She had a ''Eureka!'' moment four years ago when she saw her first regulation written in plain English.

She'd seen hundreds of ''regs'' in her years with the government, but this one - which dealt with offshore oil leases - was actually understandable.

''It was a semi-religious experience,'' she says.

Since then, the 55-year-old federal worker has been the chief evangelist for the government's ''Plain Language'' effort, which is similar to movements taking place in many businesses.

Cheek, who is temporarily working for the National Partnership for Reinventing Government, has persuaded many agencies to admit what millions of us have complained about for years: Our government does a lousy job communicating.

Cheek says the long tradition of obfuscation is a big reason many people don't trust government. It's easier to dislike somebody if you don't know what they're saying.

''The old style of writing sends a message that, 'We're the government, we're in charge and we're telling you what to do. If you're having trouble understanding it, that's your problem,' '' Cheek says.

''Plain Language sends a message that 'We're in this together and we want your help to get this job done.' ''

Cheek adds, ''How can you have a democracy if the people don't understand what the government is doing?''

Every day, agencies publish dozens of new rules in the Federal Register, the government's daily journal of rule-making.

But the Register is such a morass of legalese that the average reader often has no idea what the rules mean. It's the same with countless other government letters and directives.

Just look at how the Federal Aviation Administration tells people how to appeal an FAA decision. It's in Subchapter B, Part 11, Paragraph 11.55: ''Reconsideration of a denial or grant of exemption.''

It's a thicket of gibberish that begins, ''Except as provided in paragraph (c) of this section . . . ''

You get the idea.

But in the new Plain Language version, that section has been boiled down to a few simple questions and answers. There's no mention of paragraph (c).

The FAA is the latest federal agency to officially adopt Plain Language. Stung by a survey of pilots who said the FAA was a poor communicator, the agency vowed to improve.

Tony Fazio, the FAA's head of rule-making, was appointed to the head the effort and is now Cheek's latest disciple.

A 17-year FAA official, he had always written in the agency's technical style. Then he had his own epiphany. He analyzed his sentences with the Microsoft Word grammar checker and discovered he wrote lots of passive sentences.

But he's faced a lot of resistance from within the FAA.

''A lot of folks feel that if it's not written obtusely, it's not a regulation,'' Fazio says. ''I don't agree with that.''

Rather than trying to win over a whole department, Cheek and other crusaders aim for a few key people.

''You get converts one person at a time,'' Cheek says. ''It sort of snowballs and when you get to a certain critical mass, you have the whole agency.''

It's hard to quantify her success, but Cheek says the effort saves the government lots of money because ''there's less follow-up, fewer call-backs, less demand for more information.''

But winning converts hasn't been easy. Many federal employees feel threatened by the idea of simpler writing.

Cheek says she is surprised at their reluctance.

''I've never really understood why federal employees are afraid to take a chance. Federal employees are damn hard to fire. They are not going to be fired for turning in something written in plain language.''

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