Optional features, i.e. features preceded by expressions Expressions likesuch as "preferably", "for example", "such as" or "more particularly" should be looked at carefully to ensure that are allowed if they do not introduce ambiguity. Expressions of this kind have no limiting effect on the scope of a claim; that is to say, the feature following any such expression is In such a case, they are to be regarded as entirely optional.
These expressions introduce ambiguity and render the scope of the claim unclear if they do not lead to a restriction of the features of the claim.
For example, the wording "a method to manufacture an artificial stone, such as a clay brick" does not fulfil the requirements of Art. 84 because a clay brick is not a type of artificial stone. Hence it is unclear which product is manufactured by the method of the claim.
Analogously, the wording "the solution is heated up to between 65 and 85 °C, particularly to 90 °C" does not fulfil the requirements of Art. 84 because the temperature after the term "particularly" contradicts the range before it.