Mine Safety and Health Administration regulations require mine operators to report to the MSHA within ten days 'each accident, occupational injury, or occupational illness' that occurs at a mine. The regulation also says that whenever any of certain occupational illnesses are 'diagnosed,' the operator must similarly report the diagnosis within ten days. The occupational illnesses covered are 'silicosis, asbestosis, coal worker's pneumoconiosis, and other pneumoconioses.' An operator's failure to report may lead to citation and penalty. MSHA issued Program Policy Letters ('PPLs') intended to coordinate and convey agency policies, guidelines, and interpretations to agency employees and interested members of the public. One PPL stated that any chest x-ray of a miner who had a history of exposure to pneumonoconiosis-causing dust that rated 1/0 or higher on the International Labor Office (ILO) classification system would be considered a 'diagnosis that the x-rayed miner has silicosis or one of the other pneumonoconioses' for the purposes of reporting requirements. Another PPL stated the MSHA's position that mere diagnosis of an occupational disease or illness did not automatically entitle a miner to benefits for disability or impairment under a workers' compensation scheme. A third PPL restated the MSHA's basic view that a chest x-ray rating above 1/0 on the ILO scale constituted a 'diagnosis' of silicosis or some other pneumoconiosis. The MSHA did not follow the notice and comment requirements of 5 U.S.C. § 553 in issuing any of the three PPLs. D claimed they were exempt under Section 553. American (P) contends that the PPL’s were legislative rules and thus they needed notice and comment. D claims they are interpretive rules to interpret regulations with respect to the definition of diagnosis.