MPEP § fp8.08
Restriction to one of the following inventions is required under 35 U.S.C. 121:
I. Claim [1], drawn to [2], classified in [3].
II. Claim [4], drawn to [5], classified [6].
In brackets 3 and 6, insert CPC subclass and main group/subgroup if classified in the Cooperative Patent Classification or USPC class and subclass if classified in the United States Patent Classification. For example, if examined in CPC, enter CPC main group xxx, subgroup yyy.