PCT International Search and Preliminary Examination Guidelines
5.31 The requirement that the claims should be clear applies to individual claims and also to the claims as a whole. The clarity of the claims is of the utmost importance for the purposes of formulating an opinion on the questions of whether the claimed invention appears to be novel, to involve an inventive step and to be industrially applicable in view of their function in defining the matter for which protection is sought. Therefore the meaning of the terms of a claim should, as far as possible, be clear for the person skilled in the art from the wording of the claim alone (see also paragraph 5.20).
5.32 Each claim must set forth the scope of the invention sought to be protected with a reasonable degree of clarity. Clarity of claim language must be analyzed in light of the content of the particular application disclosure, the teachings of the prior art, and the claim interpretation that would be given by the person skilled in the art at the time the invention was made. If a person skilled in the art can determine the boundaries of the claimed invention with a reasonable degree of certainty, the claim complies with the requirement for clarity. Breadth of a claim is not to be equated with lack of clarity. If the scope of the subject matter embraced by the claims is clear, and if the applicant has not otherwise indicated that he intends the invention to be of a scope different from that defined in the claims, then the claims comply with the requirement for clarity.
5.33 An independent claim should clearly specify all of the essential features needed to define the invention except insofar as such features are implied by the generic terms used; for example, a claim to a “bicycle” does not need to mention the presence of wheels. If a claim is to a process for producing the product of the invention, then the process as claimed should be one which, when carried out in a manner which would seem reasonable to a person skilled in the art, necessarily has as its end result that particular product; otherwise, there is an internal inconsistency and therefore lack of clarity in the claim. In the case of a product claim, if the product is of a well-known kind and the invention lies in modifying it in a certain respect, it is sufficient if the claim clearly identifies the product and specifies what is modified and in what way. Similar considerations apply to claims for an apparatus.
5.34 A claim that includes vague or equivocal forms of wording which leave the reader in doubt as to the scope of a feature should be objected to for lack of clarity. A claim should not use a relative or similar term such as “thin”, “wide” or “strong” unless the term has a well-recognized meaning in the particular art, for example “high-frequency” in relation to an amplifier, and this is the meaning intended. If a term of degree appears in a claim, the examiner should determine whether one skilled in the art would be apprised of the meaning of the term either by a disclosure of a standard for measuring that degree in the description or in view of the prior art and state of the art. It may be appropriate to invite the applicant to either define or excise the term if he could do so without extending the subject matter beyond the content of the application as filed in contravention of Article 19(2) or 34(2)(b). An applicant cannot rely on an unclear term to distinguish the claimed invention from the prior art.
5.35 The area defined by the claims must be as precise as the invention allows. As a general rule, claims which attempt to define the invention, or a feature thereof, by a result to be achieved should be objected to as lacking clarity. Objection may also be raised under lack of support where the claimed scope is broader than what the description enables. However, no objection should be raised if the invention can only be defined in such terms and if the result is one which can be achieved without undue experimentation (see paragraph 5.46), for example, directly and positively verified by tests or procedures adequately specified in the description and involving nothing more than trial and error. For example, the invention may relate to an ashtray in which a smoldering cigarette end will be automatically extinguished due to the shape and relative dimensions of the ashtray. The latter may vary considerably in a manner difficult to define whilst still providing the desired effect. So long as the claim specifies the construction and shape of the ashtray as clearly as possible, it may define the relative dimensions by reference to the result to be achieved without being objected to for lack of clarity, provided that the description includes adequate directions to enable the reader to determine the required dimensions by routine test procedures.
5.36 Where the invention relates to a product, it may be defined in a claim in various ways, viz., by a chemical formula, as a product of a process or by its parameters. Definition of a product solely by its parameters may be appropriate in those cases where the invention cannot be adequately defined in any other way, provided that those parameters can be clearly and reliably determined either by indications in the description or by objective procedures which are recognized in the art. The same applies to a process related feature which is defined by parameters. This can arise, for example, in the case of macromolecular chains. Cases in which non-art recognized parameters are employed, or a non-accessible apparatus for measuring the parameters is used, may be objectionable on grounds of lack of clarity. The examiner should be aware of the possibility that applicants may attempt to employ unusual parameters to disguise lack of novelty (see paragraph 12.04).
5.37 Where a claim for an apparatus or a product seeks to define the invention by reference to features of the use to which the apparatus or product is to be put, a lack of clarity can result. This is particularly the case where the claim not only defines the product itself but also specifies its relationship to a second product which is not part of the claimed invention (for example, a cylinder head for an engine, where the former is defined by features of where it is connected in the latter). Such a claim must either set forth a clear definition of the individual product being claimed by wording the claims appropriately (for example, by substituting “connectable” for “connected”), or be directed to a combination of the first and second products (for example, “engine with a cylinder head” or “engine comprising a cylinder head”). It may also be permissible to define the dimensions and/or shape of a first product in an independent claim by general reference to the dimensions and/or corresponding shape of a second product that is not part of the claimed first product but is related to it through use (for example, in the case of a mounting bracket for a vehicle number-plate, where the bracket frame and fixing elements are defined in relation to the outer shape of the number-plate).
5.38 Particular attention is required whenever the word “about” or similar terms, such as “approximately,” are used. Such a word may be applied, for example, to a particular value (for example, “about 200°C”) or to a range (for example, “about X to about Y”). In each case, the examiner should exercise judgment as to whether the meaning is sufficiently clear in the context of the application read as a whole. Moreover, if such words as “about” prevent the invention from being unambiguously distinguished from the prior art, an objection should be raised as to lack of novelty or inventive step.
5.39 Trademarks and similar expressions characterize the commercial origin of goods, rather than the properties of the goods (which may change from time to time) relevant to the invention. Therefore the examiner should invite the applicant to remove trademarks and similar expressions in claims, unless their use is unavoidable; they may be allowed exceptionally if they are generally recognized as having a precise meaning (see also paragraph 5.34).
5.40 Expressions like “preferably,” “for example,” “such as” or “more particularly” should be looked at carefully to ensure that they do not introduce ambiguity. The examiner should regard expressions of this kind as having no limiting effect on the scope of a claim; that is to say, the feature following any such expression should be regarded as entirely optional.
5.41 Generally, the subject matter of a claim is defined by means of positive features. However, the extent of a claim may be limited by means of a “disclaimer,” a “negative limitation,” or an “exclusion;” in other words, an element clearly defined by technical features may be expressly excluded from the protection claimed, for example in order to meet the requirement of novelty. A claim may also include a negative limitation or language that defines subject matter that is not present in the claimed invention (for example, “wherein the composition is free of water”). There is nothing per se ambiguous or uncertain about a negative limitation. A negative limitation renders the claim unclear where it is an attempt to claim the invention by excluding what the applicant did not invent rather than clearly and concisely reciting what he did invent. A claim which recites the limitation “said homopolymer being free from the proteins, soaps, resins, and sugars present in natural Hevea rubber” in order to exclude the characteristics of the prior art product, is considered to be clear where each recited limitation is clear. In addition, the negative limitation “incapable of forming a dye with said oxidized developing agent” is clear because the boundaries of the patent protection sought are clear. If alternative elements are positively recited in the description, they may be explicitly excluded in the claims. The mere absence of a positive recitation is not basis for exclusion.