Claim construction starts with the language of the claim itself.
A word or phrase used consistently throughout a patent claim should be interpreted consistently. In the absence of any evidence to the contrary, it is presumed that the use of different terms in the claims connotes different meanings. As originally presented, the broadest claim provided for a screen plate, wherein the perforations of the screen plate are disposed at the bottom of grooves the direction of which substantially deviates from the flow direction of the pulp to be screened. Since the Fiedler did not have a bottom plane structure, literal infringement was not found. CAE was estopped from relying on the doctrine of equivalents, since the amendment during prosecution abandoned any claim to a bottom without any physical structure constituting a bottom plane.