If the plaintiff, his agent, or attorney, shall make oath that the names of the heirs or stockholders against whom an action is authorized by Section 17.004, Civil Practice and Remedies Code, are unknown to the affiant, the clerk shall issue a citation for service by publication. Such citation shall be addressed to the defendants by a concise description of their classification, as "the Unknown Heirs of A.B., deceased," or "Unknown Stockholders of _________________ Corporation," as the case may be, and shall contain the other requisites prescribed in Rules 114 and 115 and shall be served as provided by Rule 116.