from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
ALTERNAT. The name of a usage among diplomatists by which the rank and
places of different powers, who have the same rights and pretensions to
precedence, are changed from time to time, either in a certain regular
order, or one determined by lot. In drawing up treaties and conventions, for
example, it is the usage of certain powers to alternate, both in the
preamble and the signatures, so that each power occupies, in the copy
intended to be delivered to it, the first place. Wheat. Intern. Law, pt. 2,
c. 3, Sec. 4..