The procedures in this part specify who may petition to add a class of employees to the Cohort, the requirements for such a petition, how a petition will be selected for evaluation by NIOSH and for the advice of the Board, and the process NIOSH, the Board, and the Secretary will use to consider a petition, leading to the Secretary's final determination to accept or deny adding a class to the Cohort. The rule provides for petitions in two distinct circumstances. One circumstance is when NIOSH has attempted to conduct a dose reconstruction for a cancer claimant, under 42 CFR part 82, and finds that the dose reconstruction cannot be completed, because there is insufficient information to estimate the radiation doses of the claimant with sufficient accuracy. The second circumstance includes all other possibilities. For example, a petition may be submitted representing a class of employees whose members have yet to file claims under EEOICPA, or even have yet to be diagnosed with cancer. As required by EEOICPA (42 U.S.C. 7384l(14)(c)(ii)), the procedures in this part include formal notice to Congress of any decision by the Secretary to add a class to the Cohort, and the opportunity for Congress to expedite or change the outcome of the decision within 180 days.