3.1.7 Error margins and definitions of limits

Prior to G 2/98 (OJ 2001, 413), it was sometimes possible to claim error margins or definitions of limits which differed in the subsequent application from the original one (see T 212/88, OJ 1992, 28; T 957/91; T 65/92; T 131/92 and "Case Law of the Boards of Appeal of the EPO", 3rd ed. 1998, p. 231 et seq.). Since the facts are only comparable up to a certain point, it is not possible to say unequivocally to what extent the principles laid down earlier still apply. In the decisions below, G 2/98 was applied.

In T 201/99 claim 1 referred to a mean residence time of "1-10 minutes", whereas both priority applications disclosed the range "from about 1-6 minutes" (claim 1) or, for all the examples, a specific residence time of "about 3 minutes". The board found that the features disclosed in the priority applications provided no explicit or implicit disclosure of a process wherein the second step lasted "10 minutes". Therefore it was apparent that they were insufficient to render directly and unambiguously disclosed therein also the whole range of "1-10 minutes". The board did not accept the appellant’s argument that the upper limit of "6 minutes" for the time length of the second step was not disclosed in the priorities as a cut-off value (i.e. as possibly related to the function of the invention and its effect) and thus constituted a feature which might be modified without changing the nature of the invention.

In T 250/02 the board found that the subject-matter of a claim for a herbal essential oil in which the total amount of carvacrol and thymol was at least 55%, and preferably 70%, by weight of the said essential oil and with exact ratios of carvacrol to thymol could not be derived directly and unambiguously from a priority document only disclosing a herbal oil containing "thymol and carvacrol in levels of 55% to 65%".

Further decisions concerned with differing ranges indicated in a priority document and disputed sets of claims include T 903/97, T 909/97, T 13/00, T 136/01, T 423/01, T 788/01, T 494/03 and T 537/03.

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