28. Period of validity of provisional certificate

The provisional certificate issued under rule 27 shall be subject to such terms and conditions as may be specified therein and shall be valid for a period of twelve months from the date of issue, and the said certificate may, at the discretion of the authorised officer, be renewed for a period of not less than six months at a time as he may think fit, and shall ordinarily be not renewed for a period beyond thirty-six months from the date of issue of such certificate :

Provided that where any provisional certificate is issued or renewed as referred to in clause (f) of section 107, the said certificate may further be renewed under this rule but the total period of validity of such certificate shall not exceed thirty six months including the period prior to the appointed day and the period for which such certificate was renewed after the appointed day :

Provided further that the provisional certificate shall stand revoked with effect from the date of validity of his certificate of registration issued under section 26 or section 27, as the case may be.