The investigation of the question as to whether a union represents a major-ity of an appropriate grouping of em-ployees is initiated by the filing of a petition by any person or labor organi-zation acting on behalf of a substantial number of employees or by an em-ployer when one or more individuals or labor organizations present a claim to be recognized as the exclusive bar-gaining representative. If there is a certified or currently recognized rep-resentative, any employee, or group of employees, or any individual or labor organization acting in their behalf may also file decertification petitions to test the question of whether the cer-tified or recognized agent is still the representative of the employees. If there is a certified or currently recog-nized representative of a bargaining unit and there is no question con-cerning representation, a party may file a petition for clarification of the bargaining unit. If there is a unit cov-ered by a certification and there is no question concerning representation, any party may file a petition for amendment to reflect changed cir-cumstances, such as changes in the name or affiliation of the labor organi-zation involved or in the name or loca-tion of the employer involved. The pe-tition must be in writing and signed, and either must be notarized or must contain a declaration by the person signing it, under the penalties of the Criminal Code, that its contents are true and correct to the best of his or her knowledge and belief. It is filed with the Regional Director for the Re-gion in which the proposed or actual bargaining unit exists. Petition forms, which are supplied by the Regional Of-fice upon request, provide, among other things, for a description of the con-templated or existing appropriate bar-gaining unit, the approximate number of employees involved, and the names of all labor organizations which claim to represent the employees. If a peti-tion is filed by a labor organization seeking certification, or in the case of a petition to decertify a certified or recognized bargaining agent,the peti-tioner must supply, within 48 hours after filing but in no event later than the last day on which the petition might timely be filed, evidence of rep-resentation. Such evidence is usually in the form of cards, which must be dated, authorizing the labor organiza-tion to represent the employees or au-thorizing the petitioner to file a decer-tification petition. If a petition is filed by an employer, the petitioner must supply, within 48 hours after filing, proof of demand for recognition by the labor organization named in the peti-tion and, in the event the labor organi-zation named is the incumbent rep-resentative of the unit involved, a statement of the objective consider-ations demonstrating reasonable grounds for believing that the labor or-ganization has lost its majority status.