25.04.1 A party who makes an application is a plaintiff, and each other party is a defendant.
25.04.2 A defendant must be referred to in the title of the proceeding:
(a) if the defendant is an officer of the Commonwealth, and a writ of mandamus or prohibition is sought against the officer--by the name of the office held; or
(b) in any other case--by name, or by the name of the office held by the defendant, or both.