PCT International Search and Preliminary Examination Guidelines
5.04 The claims must be drafted in terms of the “technical features of the invention.” This means that claims should not contain any statements relating, for example, to commercial advantages or other non-technical matters, but statements of purpose should be allowed if they assist in defining the invention. It is not necessary that every feature should be expressed in terms of a structural limitation. Since it is a matter for national law, the examiner should normally not object to the inclusion of functional limitations in a claim provided that a person skilled in the art would have no difficulty in providing some means of performing this function without exercising inventive skill or that such means are fully disclosed in the application concerned. A functional limitation must be evaluated and considered, just like any other limitation of the claim, for what it fairly conveys to a person skilled in the art in the context in which it is used. Claims to the use of the invention in the sense of the technical application thereof are permissible. See paragraph 5.21.
5.05 Rule 6.3(b) defines the two-part form which a claim should take “whenever appropriate.” The first part should contain a statement indicating the designation of the subject matter of the invention, that is, the general technical class of apparatus, process, etc., to which the claimed invention relates, followed by a statement of those technical features “which are necessary for the definition of the claimed subject matter but which, in combination, are part of the prior art.” It is clear from this wording that it is necessary only to refer to those prior art features which are relevant to the invention. For example, if the invention relates to a photographic camera but the claimed inventive step relates entirely to the shutter, it would be sufficient for the first part of the claim to read: “A photographic camera including a focal plane shutter having...” (here recite the known combination of features which is utilized) and there is no need to refer also to the other known features of a camera such as the lens and viewfinder. The second part or “characterizing portion” should state the technical features which, in combination with the features stated under the first part (Rule 6.3(b)(i)), it is desired to protect, that is, the features which the invention adds to the prior art. If the search results, or any additional documents considered to be relevant in accordance with Article 33(6), reveal that any feature in the second part of the claim was, in fact, already known in combination with all the features in the first part of the claim and in that combination have the same effect as they have in the full combination according to the claimed invention, the examiner may invite the applicant to transfer such feature or features to the first part. Where, however, a claim relates to a novel combination, and where the division of the features of the claim between the prior art part and the characterizing part could be made in more than one way without inaccuracy and if the division of the features chosen by the applicant is not incorrect, the examiner should take no action. If the examiner, in the first written opinion, invites the applicant to adopt a different division but the applicant does not follow the invitation, the examiner should not pursue the matter further since the manner of claiming is a matter for national laws of designated or elected States.
5.06 The applicant may be invited to follow the above two-part formulation where, for example, it is clear that the applicant’s invention resides in a distinct improvement in an old combination of parts or steps. However, as is indicated by Rule 6, this form need only be used in appropriate cases. The nature of the invention may be such that this form of claim is unsuitable, for example, because it would give a distorted or misleading picture of the invention or the prior art. Examples of the kind of invention which may require a different presentation are:
5.07 In examples (i) and (ii), the two-part form of claim according to Rule 6.3(b) may be artificial and inappropriate, whereas, in example (iii), it might lead to an inordinately lengthy and involved claim. Another example in which the two-part form of claim provided for in Rule 6.3(b) may sometimes be inappropriate is where the claimed invention is a new chemical compound or group of compounds that does not fall within a known class. It is also likely that other cases will arise in which it will be appropriate to formulate the claim in a different form.
5.08 When determining whether or not to invite the applicant to put a claim in the two-part form provided by Rule 6.3(b), it is important to assess whether this form is “appropriate.” In this respect, it should be borne in mind that the purpose of the two-part form of claim is to allow the reader to see clearly which features necessary for the definition of the claimed subject matter are, in combination, part of the prior art. If this is sufficiently clear from the indication of prior art provided in the description, to meet the requirement of Rule 5.1(a)(ii), it is appropriate to present the claim in a form other than the two-part form provided by Rule 6.3(b).
5.09 The claims, as well as the description, “may contain chemical or mathematical formulae” but not drawings. “Any claim may contain tables” but “only if the subject matter of the claim makes the use of tables desirable.” In view of the use of the word “desirable,” the examiner should not object to the use of tables in claims where this form is convenient.
5.10 The claims must not, in respect of the technical features of the invention, rely on references to the description or drawings “except where absolutely necessary.” In particular, they must not normally rely on references such as: “as described in part ... of the description” or “as illustrated in Figure 2 of the drawings.” The emphatic wording of the excepting clause should be noted. Thus, the applicant should be invited to show that it is “absolutely necessary” to rely on reference to the description or drawings in appropriate cases. An example of an exception would be that in which the invention as claimed involved some peculiar shape illustrated in the drawings but which could not be readily defined either in words or by a simple mathematical formula. Another special case is that in which the invention relates to chemical products whose features can be defined only by means of graphs or diagrams.
5.11 If there are drawings and the technical features of the claims would be rendered more intelligible by relating those features to the corresponding features of the drawings, this should preferably be done by placing the appropriate reference signs in parentheses after the features in the claims. This should be done in both parts of claims having the preferred form specified in Rule 6.3(b). These reference signs are not, however, to be construed as limiting the scope of a claim, but merely as aids to an easier understanding of the defined subject matter.