Task: songer_civproc1

What follows is an opinion from a United States Court of Appeals.
Your task is to identify the most frequently cited federal rule of civil procedure in the headnotes to this case. Answer "0" if no federal rules of civil procedure are cited. For ties, code the first rule cited.

PER CURIAM.
The sole question presented to this court in this case, namely, whether the Postmaster General of the United States is an indispensable party to a suit of this nature, has been heretofore decided by this court, and the question is no longer open to dispute. We held, in Neher v. Harwood, Postmaster, etc., 9 Cir., 128 F.2d 846, 852, that the Postmaster General was an indispensable party in an action to enjoin a postmaster from carrying into effect a “fraud” order issued by the Postmaster General under 39 U.S. C.A. § 259.
Accordingly, the order of the court below is affirmed.

Question: What is the most frequently cited federal rule of civil procedure in the headnotes to this case? Answer with a number.
Answer:

Answer: 0