Alternative Expressions in Claims.
In an older (and now-defunct) U.S. patent practice, the use of the terms “or” and “either” in a patent claims was considered an improper use of an alternative expression. According to the present MPEP § 2173.05(h), however, alternative expressions are now permitted if they present no uncertainty or ambiguity with respect to the question of scope or clarity of the claims. For example, a claim reciting “wherein R is A, B, C or D” is perfectly acceptable in modern practice.
One form of alternative expression is commonly referred to as a Markush group, named after Eugene Markush, the first inventor (1920’s) to use the claim form successfully in a patent. Markush language recites members as being ‘‘selected from the group consisting of A, B, and C.’’ Thus, the Markush group language can be used to claim elements in the alternative without resorting to the the term “or.” Markush claims are typically employed in the chemical, pharmaceutical, biotech and material arts, but the language is equally acceptable (and useful) in the mechanical and electrical patents.
JW Note: Although accepted by the USPTO, many practitoners (including yours truly) typically try to avoid using the term “or” and especially “and/or” in drafting claims. We will instead rely on the more traditional Markush language, or other creative verbiage, e.g., “wherein R is one of A, B, and a combination thereof.”