The Clinton administration is expected to issue a final rule today requiring virtually all the nation's employers to create programs to protect workers from the repetitive stress strains and pain of the workplace. The sweeping new standard, eight years in the making, is the most costly ever to come out of the Occupational Safety and Health Administration. It will cover 6 million workplaces and more than 100 million workers in nearly every line of business. The rule is so bitterly opposed by many industry groups that a congressional move to block its unveiling torpedoed a year-end budget agreement with the White House two weeks ago, forcing the lame-duck session of Congress. Lawyers for trade associations said they will sue to overturn the rule as soon as it is published. The final rule mandates that the science of ergonomics be brought to the workplace, requiring employers to better fit jobs to the physical limitations of their workers. OSHA officials said their goal is to cut in half during the next decade the 600,000 repetitive stress injuries that result in lost work time each year. The hospital, restaurant, grocery, and trucking and courier industries will need to make the most changes in the workplace, OSHA predicted. The rule also targets the millions of workers who sit in front a computer screen all day, typing and using a mouse.