MPEP Transitional Phrases #0024

The transitional phrases “comprising”, “consisting essentially of” and “consisting of” define the scope of a claim with respect to what unrecited additional components or steps, if any, are excluded from the scope of the claim.

The transitional term “comprising”, which is synonymous with “including,” “containing,” or“ characterized by,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

The transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim.

 -  A claim which depends from a claim which “consists of” the recited elements or steps cannot add an element or step. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

The transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed invention.

 - A ‘consisting essentially of’ claim occupies a middle ground between closed claims that are written in a ‘consisting of’ format and fully open claims that are drafted in a ‘comprising’ format.

MANUAL OF PATENT EXAMINING PROCEDURE
§ 2111.03 Transitional Phrases [R-08.2012]