The Occupational Safety and Health Administration letter that warned a Texas employer it was responsible for the safety of its at-home workers was unusual because of the commotion it caused before being quickly withdrawn. It is not out of the ordinary, however, for OSHA and other regulatory agencies to issue such guidance. In fact, regulators have written thousands of pages of such guidance over the years to explain existing policies, clarify obligations, give advice and dole out information on scores of subjects.

Not only is guidance from federal agencies common, but it comes in many shapes and sizes, from directives and interpretive letters to training manuals, speeches, news releases, texts for slide shows, bulletins and policy documents.

Much of this comes in response to specific questions from companies that are affected by particular rules. They write to the agency--as CSC Credit Services in Houston did to OSHA--to get a read on how regulators view their situation.

OSHA's interpretive letter to the Texas company on its telecommuting workers set off a firestorm of opposition from the business community and members of Congress and called into question the relevance of guidance, its applicability and its legal effect on companies.

The business community's interpretation was that OSHA's letter amplified the agency's rules without a formal rule-making.

After Congress passes a law, federal agencies write regulations to implement the law. That rule-making procedure is governed by elaborate rules, requiring an opportunity for public comment before final decisions are made. Final rules then can be challenged in court.

The rule-making process has become more laborious and contentious in recent years as Congress has added more requirements that agencies must meet to justify starting the procedure.

Many industries and their friends in the Republican-controlled Congress view agencies' use of less-formal guidance as a way for the Clinton administration to avoid the strictures of the rule-making process.

Since October, a House subcommittee has been investigating how OSHA, the National Highway Traffic Safety Administration and the Environmental Protection Agency use guidance. It plans to hold a hearing next month and will have on display 1,641 documents adding up to 39,756 pages of guidance submitted by OSHA. To comply with the subcommittee's request, it cost the agency $23,600 to have a contractor gather and organize the documents.

Experts in administrative law and legal practitioners at federal agencies cite nuanced definitions of what constitutes guidance and how much weight it should be given by the regulated parties. Some companies have challenged the practice of agencies issuing guidance that makes new policy or expands an existing policy, saying they should have proposed a formal rule instead, so the company could comment on it.

"This is a tricky area. It's hard to parse some of these questions," said Jeffrey Lubbers, a professor of administrative law at American University. Lubbers said there are provisions in the rule-making law that allow agencies to give guidance without going through a formal regulatory process.

He said the law recognizes that it's a good idea to give the public guidance and be responsive. "But it's not good to apply a statement of policy as a binding regulation because people haven't been able to comment on it," Lubbers said.

Robert Anthony, a law professor at George Mason University, said agencies sometimes issue directives that have practical effect on companies even though they may not be legally binding. Companies then feel obligated to comply, or take their objections to court. Anthony calls these "non-rule rules."

Anthony said avoiding the rule-making process this way expands an agency's regulatory authority "in a most undesirable way" and allows it to change its mind later. To avoid any confusion, Anthony suggested that OSHA's telecommuter-safety interpretation should have been issued as a formal proposal that called for comment.

NHTSA, on the other hand, goes out of its way, on its World Wide Web site, to tell readers that they should not infer that interpretations written for others necessarily apply to them. "Critical factual differences may exist between your situation and those addressed in previous interpretations," it says.

An NHTSA official said guidance is valuable to people because "they want some certainty."

"They want to know how we think," the official said. "But it's not binding in a technical sense." NHTSA considers its famous admonishment to drivers to "buckle up" to be guidance.

In a statement, OSHA said it "posts numerous documents on the Internet to provide information as broadly as possible. In addition to letters, OSHA posts standards, directives, bulletins, training materials, news releases, speeches and more." In correspondence with the House subcommittee investigating the practice, the agency stated that in some cases, Congress required such assistance to the public.

"I am troubled by the underlying assumption . . . that a large volume of informal guidance by an agency is, in itself, a problem. Our efforts are ongoing, have been well received, and we plan to continue with them," said Sally Paxton, the deputy solicitor for national operations for the Labor Department, of which OSHA is a part.

EPA officials said they provide "an adjudication," or order, to parties who ask for interpretations. The response is intended for that party, though the agency may publish it more widely. "None are legally binding," said an EPA lawyer. "The regulated community doesn't misunderstand what these things mean."

The subcommittee will make the point that companies and citizens don't have to pay heed to most of these documents--even though they may use words such as "must" and "require"--an aide there said. It also will push legislation that would force agencies to state explicitly that guidance documents that don't qualify as formal rules are "non-binding" on the public.

Some would prefer not having such a disclaimer in some cases. Patrick Cleary of the National Association of Manufacturers said of the OSHA letter flap: "I'm glad it's legally binding, because it's stupid. It does provide some clarity on what the law is even though we don't like what the law says."

The guidance issue "is confusing to the regulated public," said a staffer to Rep. David M. McIntosh (R-Ind.), the subcommittee chairman.

The aide said, for example, that there are dozens of documents dispensing guidance on ergonomic issues when there is no specific ergonomics rule on the books.