T 2017/07 (Hair dye composition/KAO) of 26.11.2009

A composition which is specified in a claim to comprise a component in an amount which is defined by a numerical range of values is subject to an implicit proviso excluding the presence of that component in an amount outside of that range.

An amendment restricting the breadth of that component, for instance by narrowing down a generic class or a list of chemical compounds defining that component, has the consequence of limiting the scope of this implicit proviso.

A composition which is defined as comprising the components indicated in the claim is open to the presence of any further components, unless otherwise specified.

In a claim directed to such an openly defined composition, the restriction of the breadth of a component present therein may have the effect of broadening the scope of protection of that claim, with the consequence that in opposition/appeal proceedings such amended claim may extend the protection conferred by the granted patent (Article 123(3) EPC).