Amendment of obvious errors, of transposition of letters in words of common knowledge, or of omissions on birth certificates may be made by the department within the first year after the date of the birth, either upon its own observation, upon query, or upon request of a person with a direct and tangible interest in the certificate. When such additions or minor amendments are made by the department, a notation as to the source of the information together with the date the change was made and the initials of the authorized agent making the change shall be made on the reverse side of the certificate in such a way as not to become a part of the certificate. The certificate shall not be marked amended.