In an application to revoke EP(UK)1355604 a key question to be answered was the meaning in the claims of the terms “vent sites” and “bond sites”. Both terms were used interchangeably in the associated patent specification and both terms were given the same reference numeral 100.
A starting point on the use of reference numerals in the construction of a patent claim is to be found in the ruling of Jacob LJ in Virgin Atlantic v Premium Aircraft in which Jacob said:
“…we do not think that numerals should influence the construction of the claim at all – they do not illustrate whether the inventor intended a wide or narrow meaning. The patentee is told by the rule that if he puts numerals into his claim they will not be used to limit it. If the court subsequently pays attention to the numbers to limit the claim that is simply not fair. And patentees would wisely refrain from inserting numbers in case they were used against them.”
Based on this direction a claim including a reference numeral for a feature from one embodiment but not an additional reference numeral for the corresponding feature in another embodiment is not to be construed in a way that restricts what is defined to just the referenced embodiment. The reference numerals should not be used to limit the ambit of the claim. Thus to this extent reference numerals should indeed be ignored when construing claims.
However, in Joa, Hacon J considered that because a reference number could be used to establish a relationship between one feature and another in an embodiment i.e. to conclude that a lid was part of a main body, and the claim construed accordingly, it was appropriate to take reference numerals into account to some extent.
Thus the fact that “vent sites” and “bond sites” were consistently referred to in the specification by the same reference numeral in fact clarified an interchangeability of the features and this should be accounted for when construing the corresponding terms or words in a claim.
Patent draughtsmen should take note and consider carefully the use of multiple words to describe the same thing in any patent specification. They should likewise consider carefully the risk caused by accidentally referencing different features with the same reference numeral.
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