Rule 322. Authority for appearance of attorney in real property action. (a) Authority of plaintiff's attorney. Where the defendant in an action affecting real property has not been served with evidence of the authority of the plaintiff's attorney to begin the action, he may move at any time before answering for an order directing the production of such evidence. Any writing by the plaintiff or his agent requesting the attorney to begin the action or ratifying his conduct of the action on behalf of the plaintiff is prima facie evidence of the attorney's authority. (b) Authority of non-resident defendant's attorney. The attorney for a non-resident defendant in an action affecting real property shall file with the clerk written authority for his appearance, executed and acknowledged in the form required to entitle a deed to be recorded, and shall serve either a copy of such authority or notice of such filing on the plaintiff's attorney within twenty days after appearing or making a motion. (c) Agencies or wholly-owned corporations of the United States. This rule does not apply to an attorney representing an official, agency or instrumentality of, or corporation wholly owned by, the United States.