Every employee must declare on his first appointment or on being required to do so by the Management, his date of birth according to the Christian Era and produce confirmatory documentary evidence, e.g. Matriculation Certificate or Municipal/Police/Birth Certificate etc., and in the absence there of, such evidence as may be acceptable to the Management. If any employee is unable to produce documentary evidence of his age, he shall make a written declaration regarding his age. The date of birth once recorded in the Service Book/sheet of the employee as stated above will not be altered except in the case of clerical error, or on production of proof acceptable to the management provided that the proof is produced within one year of the date on which the original date of birth was recorded in the service book/sheet.”