48 CFR § 52.105 - Procedures for using alternates.
(a) The FAR accommodates a major variation in a provision or clause by use of an alternate. The FAR prescribes alternates to a given provision or clause in the FAR subject text where the provision or clause is prescribed. The alternates to each provision or clause are titled “Alternate I,” “ Alternate II,” “Alternate III,” etc.
(b) When an alternate is used, its date shall be cited along with the date of the basic provision or clause; e.g., 52.209-3 FIRST ARTICLE APPROVAL— CONTRACTOR TESTING (OCT 1983)—ALTERNATE I (DEC 1983).
(c) Under certain circumstances, a provision or clause may be used with two or more alternates. In these circumstances, each of the applicable alternates shall be cited, whether incorporated by reference or in full text; e.g., 52.209-3 FIRST ARTICLE APPROVAL—CONTRACTOR TESTING (OCT 1983)—ALTERNATE I (DEC 1983) AND ALTERNATE II (FEB 1984). However, under no circumstances may an alternate to a specific provision or clause be applied to any other provision or clause.