PCT International Search and Preliminary Examination Guidelines


Chapter 4 Content of the International Application (Other Than the Claims)


Article 5

4.02  The international application must “disclose the invention in a manner sufficiently clear and complete for the invention to be carried out by a person skilled in the art.” The meaning of “person skilled in the art” is discussed in paragraph 13.11. This requirement of disclosure should be met by the description with the aid of drawings, if any. The provisions relating to the content of the description are set out in Rule 5. The purposes of these provisions are:

(i) to ensure that the international application contains all the technical information required to enable a skilled person to put the invention into practice; and

(ii) to enable the reader to understand the contribution to the art which the inventor has made.

Rule 5.1

4.03  The description should start with the same title that appears in the request (Form PCT/RO/101). The description should contain subheadings corresponding to those contained in Section 204 (“Technical Field”, “Background Art”, “Disclosure of Invention”, “Brief Description of Drawings”, “Best Mode(s) for Carrying Out the Invention”, and “Industrial Applicability”. The use of such subheadings is strongly recommended in order to provide uniformity in publication and to facilitate access to the information contained in the international application. Some of the recommended subheadings are discussed in the following paragraphs.

Technical Field

Rule 5.1(a)(i)

4.04  The application should specify the technical field to which it relates.

Background Art

Rules 5.1(a)(ii), 6.3(b)(i)

4.05  The description should also mention any background art of which the applicant is aware, and which can be regarded as useful for understanding the invention and its relationship to the prior art; identification of documents reflecting such art, especially patent specifications, should preferably be included. For further guidance concerning the statement of prior art, see the appendix to this chapter. This applies in particular to the background art corresponding to those technical features of the invention which are necessary for the definition of the claimed subject matter but which, in combination, are part of the prior art (see Rule 6.3(b)(i) and paragraph 5.05).

Disclosure of Invention

Rules 5.1(a)(iii), 9.1(iii)

4.06  The invention as claimed should be disclosed in such a way that the technical problem, or problems, with which it deals can be appreciated and the solution can be understood. To meet this requirement, only such details should be included as are necessary for elucidating the invention. Where the invention lies in realizing what the problem is (see Chapter 13), this should be apparent, and, where the means of solving the problem (once realized) are obvious, the details given of its solution may, in practice, be minimal.

4.07  When there is doubt, however, as to whether certain details are necessary, the examiner should not require their excision. It is not necessary, moreover, that the invention be presented explicitly in problem and solution form. Any advantageous effects which the applicant considers the invention to have in relation to the prior art should be stated, but this must not be done in such a way as to disparage any particular prior product or process. The prior art nor the applicant’s invention cannot be referred to in a manner likely to mislead. This might be done, for example, by an ambiguous presentation which gives the impression that the prior art had solved less of the problem than was actually the case. Fair comment as referred to in paragraph 4.30 is permitted. Regarding amendment to, or addition of, a statement of problem, see paragraph 20.18.

Brief Description of Drawings

4.08  If drawings are included they should first be briefly described, in a manner such as: “Figure 1 is a plan view of the transformer housing; Figure 2 is a side elevation of the housing; Figure 3 is an end elevation looking in the direction of the arrow ‘X’ of Figure 2; Figure 4 is a cross-section taken through AA of Figure 1.” When it is necessary to refer in the description to elements of the drawings, the name of the element should be referred to as well as its number, that is, the reference should not be in the form “3 is connected to 5 via 4” but “resistor 3 is connected to capacitor 5 via switch 4.”

4.09 The description and drawings should be consistent with one another, especially in the matter of reference numbers and other signs (see paragraph 4.28). However, where, as a result of amendments to the description, whole passages are deleted, it may be tedious to delete all superfluous references from the drawings and in such a case the examiner need not pursue too rigorously the consistent use of reference signs as between the description and the drawings. The reverse situation should not occur, that is, all reference numbers or signs used in the description or claims should also appear on the drawings.

Best Mode for Carrying Out the Invention

Rule 5.1(a)(v)

4.10 The international application should set forth at least the best mode contemplated by the applicant for carrying out the invention claimed; this should be done in terms of examples, where appropriate, and with reference to the drawings, if any. The applicant need not point out which of the embodiments or examples is considered to be the best mode. Determining compliance with the best mode requirement requires a two-prong inquiry. First, it must be determined whether, at the time the application was filed, the applicant contemplated a best mode for practicing the invention. This is a subjective inquiry which focuses on the applicant’s state of mind at the time of filing. Second, if the inventor did, in fact, contemplate a best mode, it must be determined whether the written description disclosed the best mode such that a person skilled in the art could practice it. This is an objective inquiry, focusing on the scope of the claimed invention and the level of skill in the art. The examiner should assume that the best mode is disclosed in the application, unless evidence is presented that is inconsistent with that assumption. It is therefore extremely rare that an objection based upon a lack of best mode would be made in an international application. There currently are diverging practices among the International Authorities and designated States with respect to the requirement for the application to set forth the best mode. Where the national law of a designated State does not require the description of the best mode but is satisfied with the description of any mode (whether it is the best contemplated or not), failure to describe the best mode contemplated has no effect in that State.

Structure and Function

4.11 In order that the requirements of Article 5 and of Rule 5.1(a)(iii) and (v) may be fully satisfied, it is necessary that the invention be described not only in terms of its structure but also in terms of its function, unless the functions of the various parts are immediately apparent. Indeed, in some technical fields (for example, computers), a clear description of function may be much more appropriate than an over-detailed description of structure.


4.12  It is the responsibility of the applicant to ensure that he supplies, when he first files his international application, a sufficient disclosure, that is, one that meets the requirements of Article 5 in respect of the invention, as claimed in all of the claims (see paragraphs 5.43 to 5.53). If the disclosure is seriously insufficient, such a deficiency cannot be cured subsequently by adding further examples or features without offending against Article 34(2)(b) which requires that the subject matter content of the application must not go beyond the disclosure in the international application (see paragraphs 20.03 and 20.10 et seq.). Where the disclosure is insufficient to enable a person skilled in the art to carry out the claimed invention, the claim may also be too broad to be supported by the description and drawings. Therefore, in that case, there may be non-compliance with both the requirement concerning sufficiency under this paragraph and the requirement of support of the claims (see paragraphs 5.54 to 5.58).

4.13  Occasionally international applications are filed in which there is a fundamental insufficiency in the invention in the sense that it cannot be carried out by a person skilled in the art; there is then a failure to satisfy the requirements of Article 5 which is essentially irreparable. Two instances thereof deserve special mention:

(a) The first is where the successful performance of the invention is dependent on chance. That is to say, a person skilled in the art, in following the instructions for carrying out the invention, finds either that the alleged results of the invention are not reproducible or that success in obtaining these results is achieved in a totally unreliable way. An example where this may arise is a microbiological process involving mutations. Such a case should be distinguished from one where repeated success is assured even though accompanied by a proportion of failures as can arise, for example, in the manufacture of small magnetic cores or electronic components; in this latter case, provided the satisfactory parts can be readily sorted by a nondestructive testing procedure, no objection necessarily arises under Article 5.

(b) The second instance is where successful performance of the invention is inherently impossible because it would be contrary to well-established physical laws. This applies, for example, to a perpetual motion machine (see paragraph 4.06).

Industrial Applicability

Article 33(1), (4); Rule 5.1(a)(vi)

4.14  Refer to chapter 14 for discussion of the industrial applicability of the invention.

Nucleotide and/or Amino Acid Sequence Listings

Rule 5.2; Section 208; AI Annex C

4.15 Where the international application contains disclosure of any nucleotide and/or amino acid sequence having ten or more specifically defined nucleotides or four or more specifically defined amino acids, the description should contain a separate sequence listing part complying with the standard provided for in Annex C of the Administrative Instructions. For handling of the nucleotide and/or amino acid sequence listings, refer to paragraphs 9.39, 15.12 and 15.14A (search stage) and paragraphs 18.17 and 18.18 (examination stage).

Deposit of Biological Material

Rule 13bis

4.16  The term “biological material” means any material containing genetic information and capable of reproducing itself or of being reproduced in a biological system. Where the application refers to biological material which cannot otherwise be described in the application to meet the sufficiency of disclosure requirements of Article 5, the deposit of such material is taken into consideration when determining whether those requirements have been met.

4.17  The deposit is considered part of the description to the extent that the requirements regarding sufficiency of disclosure under Article 5 cannot otherwise be complied with; thus the deposit would be taken into account in determining compliance with such requirements. Therefore, mere reference to the deposited material in an application may not be sufficient to replace the explicit disclosure of such material in the application in order to comply with the sufficiency of disclosure requirements. It should be noted, however, that a reference to the deposit in the application would not create the presumption that the deposit is necessary or required to comply with those requirements.

4.18  In accordance with paragraphs 4.16 and 4.17, a deposit of biological material is taken into consideration in determining whether the sufficiency of disclosure requirements of Article 5 has been met. Further, in some Authorities, a deposit of biological material is also taken into consideration in determining whether the support requirement of Article 6 has been met.

References to Deposited Microorganisms or Other Biological Material as Part of the Description

Rule 13bis.7

4.19 The national law of certain States requires that references to deposited microorganisms or other biological material furnished under Rule 13bis.3(a) be included in the description (see the PCT Applicant’s Guide, Annex L). Where such a State is designated and indications are presented on a separate sheet such as Form PCT/RO/134 (which may be prepared using the PCT-SAFE software), that sheet should be numbered as a sheet of the description, but this matter is not considered by the International Authority.

Requirements as to the Language of Sheets Containing References to Deposited Microorganisms or Other Biological Material

Articles 11(1)(ii), 14(4); Rules 29.3, 30

4.20  Sheets containing references to deposited microorganisms or other biological material must, if they are part of the description, be in the same language as that of the description. This is a requirement for being accorded an international filing date (Article 11(1)(ii), see paragraph 41 of the PCT Receiving Office Guidelines). If the International Searching Authority discovers less than four months from the international filing date that, despite an international filing date having been accorded, these sheets are not in the same language as that of the description, it notifies the receiving Office using Form PCT/ISA/209, indicating that it considers that the receiving Office should make a finding that the international application is to be considered withdrawn under Article 14(4). If the receiving Office does not make such a finding within four months of the international filing date, the international application cannot be so considered withdrawn and the deficiency is merely noted in the written opinion (see paragraph 17.49). The applicant may then file an appropriate correction or (if international preliminary examination is demanded) amendment.


Rule 5.1(b); Section 204

4.21  The manner and order of presentation of the various parts of the description should be that specified in Rule 5.1(b) and Section 204 (see paragraph 4.03), unless, “because of the nature of the invention, a different manner or a different order would result in a better understanding and a more economic presentation.” Since the responsibility for a clear and complete description of the invention lies with the applicant, the examiner should exercise his discretion as to whether to object to the presentation. Some departure from the requirements of Rule 5.1(a) is acceptable, provided the description is clear and orderly and all the requisite information is present. For example, the requirements of Rule 5.1(a)(iii) (see paragraph 4.06) may be waived where the invention is based on a fortuitous discovery, the practical application of which is recognized as being useful, or where the invention breaks entirely new ground. Also certain technically simple inventions may be fully comprehensible with the minimum of description and but slight reference to prior art.

Rule 10.2

4.22  The description should be clear and straightforward with avoidance of unnecessary technical jargon. In general, only such technical terms, signs and symbols should be used as are generally accepted in the art. Little known or specially formulated technical terms may be allowed, provided that they are adequately defined and that there is no generally recognized equivalent. This discretion may be extended to foreign terms when there is no equivalent in the language of the international application. Terms already having an established meaning must not be used to mean something different as this is likely to cause confusion. There may be circumstances where a term may legitimately be borrowed from an analogous art. Terminology and signs should be consistent throughout the international application.

4.23  In the particular case of inventions in the computer field, program listings in programming languages cannot be relied on as the sole disclosure of the invention. The description, as in other technical fields, should be written substantially in normal language, possibly accompanied by flow diagrams or other aids to understanding, so that the invention may be understood by those skilled in the art. Short excerpts from programs written in commonly used programming languages can be accepted if they serve to illustrate an embodiment of the invention.

Rule 10.1(a), (b), (d), (e)

4.24  When the properties of a material are referred to, the relevant units should be specified if quantitative considerations are involved. If this is done by reference to a published standard (for example, a standard of sieve sizes), and such standard is referred to by a set of initials or similar abbreviation, it should be adequately identified in the description. The metric system of units of weight and measures should be used or, if another system is used, the units should additionally be expressed in the metric system. Similarly, temperature should be expressed in degrees Celsius or also expressed in degrees Celsius if first expressed in a different manner. Other physical values (that is, other than those having units directly derivable from length, mass, time and temperature) should be expressed in the units recognized in international practice; for example, for electric units the MKSA (Meter, Kilogram, Second, Ampere) or SI (Système International) systems should be used. Chemical and mathematical symbols, atomic weights and molecular formulae should be those in general use, and technical terms, signs and symbols should be those “generally accepted in the art.” In particular, if there are any agreed international standards in the art in question, these should be adopted wherever practicable.

4.25  The use of proper names or similar words to refer to materials or articles is undesirable insofar as such words merely denote origin or where they relate to a range of different products. If such a word is used, then in order to satisfy the requirements of Article 5, the product should normally be sufficiently identified, without reliance upon the word, to enable the invention to be carried out by a person skilled in the art. However, where such words have become internationally accepted as standard descriptive terms and have acquired a precise meaning (for example, “Bowden” cable, “Bellville” washer), they may be allowed without further identification of the product to which they relate.

4.26  References in international applications to other documents may relate either to the background art or to a part of the disclosure of the invention. Where the reference relates to the background art, it may be in the application as originally filed or introduced at a later date (see paragraph 20.18). Where the reference relates directly to the disclosure of the invention (for example, details of one of the components of a claimed apparatus) then, if it is to be taken into account in respect of Article 5, it must be in the application as originally filed and clearly identify the document referred to in such a manner that the document can be easily retrieved. If matter in the document referred to is essential to satisfy the requirements of Article 5, this matter should be incorporated into the description, because the patent specification should, regarding the essential features of the invention, be self-contained, that is, capable of being understood without reference to any other document.

4.27  A reference in the description to an unpublished, previously filed application (that is, not published before the international filing date) should not be regarded as being part of the disclosure, unless the application referred to is made available to the public on or before the publication date of the international application. The reference to such an application made available to the public on or before the publication date of the international application may be replaced by the actual text referred to and may be taken into account by the examiner. Similarly, references to textbooks and periodicals are allowable under the same conditions if it can be proved that the content thereof was fixed prior to the international filing date. In the case of any document made available to the public later than the publication date of the international application or not to be published at all (for example, an application withdrawn before publication), the examiner should not take into account the reference to that document for the purposes of international preliminary examination. It should be noted, however, that this practice relates only to the international phase and does not preclude any designated or elected Office applying the relevant national law as far as it relates to the contents of the disclosure of the international application as filed.