The description and designation in an indictment of the accused person, or of any other person to whom reference is made therein, shall be such as is reasonably sufficient to identify him without necessarily stating his correct name, or his abode or occupation; and if for any reason it is impracticable to give such a description or designation, such description or designation shall be given as is reasonably practicable in the circumstances, or such person may be described as "a person unknown" .