29 CFR 102.20: Answer to complaint; time for filing; contents; allegations not denied deemed admitted.

The Respondent must, within 14 days from the service of the complaint, file an answer. The Respondent must specifically admit, deny, or explain each of the facts alleged in the complaint, unless the Respondent is without knowledge, in which case the Respondent must so state, such statement operating as a denial. All allegations in the complaint, if no answer is filed, or any allegation in the complaint not specifically denied or explained in an answer filed, unless the Respondent states in the answer that the Respondent is without knowledge, will be deemed to be admitted to be true and will be so found by the Board, unless good cause to the contrary is shown.