To the extent that the requirements of Article 84 EPC can only be fulfilled, in relation to a claim which is characterised by a functional feature defining a result to be achieved, if the feature is such that a person skilled in the art can, without exceeding his normal knowledge and skills, not only understand it, but also without undue burden implement it, the former requirement (understanding) is one of clarity and the latter (implementing) is one of support, both in the sense of Article 84 EPC. Furthermore, the latter requirement, viewed in relation to the disclosure as a whole, is highly relevant to the queston of sufficiency, in the sense of Article 83 EPC (following T 409/91, OJ EPO 1994, 653).