A Markush claim is a type of patent claim that recites a list of alternatively useable members. The key characteristics of a Markush claim are: It lists specified alternatives within a claim The alternatives are selected from a closed group "consisting of" the listed members The members share a "single structural similarity" and a common use As stated in the MPEP: A "Markush" claim recites a list of alternatively useable members. In re Harnisch, 631 F.2d 716, 719-20, 206 USPQ 300, 302-304 (CCPA 1980); Ex parte Markush, 1925 Dec. Comm'r Pat. 126, 127 (1924). To learn more: Markush claim patent claim format claim construction