The claims shall define the matter for which protection is sought. They shall be clear and concise and be supported by the description.


The aspect of clarity has two aspects:

  • Claims shall be clear in the sense that the reader must be able to understand their words and (sub-)sentences
  • Claims shall be clair in their purpose of defining the matter sougth to be protected. This requirement implies, for instance, that the claimed features must be suitable, and, in toto, sufficient to achieve the intended effects or, in other words to solve the underlying problem. (T 41/91)

Not all features of an invention have to be included in a claim. Features that are not essential and a skilled person knows to derive theses features

  • from the claim itself
  • from the description, or
  • from his general knowledge

do not contravene to the clarity of a claim (T 41/91).


Functional claims are often used for chemical inventions where it is otherwise difficult to get adequate scope of protection. But also for inventions in the domain of electronics functional claims are considered to meet the clarity requirement of Article 84 EPC if the functions themselves are specified in a clear manner in the claim and are such that a skilled person would know how to implement them using "physical" means specified in the claim, i.e. receiving means, memory and a logically programmed microprocessor (T 273/00).