When examining whether or not a claim is to be put in the form provided for in Rule 43(1), second sentence, it is important to assess whether this form is "appropriate". In this respect the purpose of the two-part form is to allow the skilled person to see clearly which features necessary for the definition of the claimed subject-matter are, in combination, part of the prior art.

Subject to what is stated in F‑IV, 2.3.2, final sentence, applicants are required to follow the above two-part formulation in their independent claim or claims, where, for example, it is clear that their invention resides in a distinct improvement in an old combination of parts or steps. However, as is indicated by Rule 43, this form need be used only in appropriate cases.

The claims must be drafted in terms of the "technical features of the invention". This means that claims must not contain any statements relating, for example, to commercial advantages or other matters not related to "carrying out" the invention, but statements of purpose are allowed if they assist in defining the invention.[Rule 43(1); ]

It is not necessary that every feature is expressed in terms of a structural limitation.

The application must contain "one or more claims".[Art. 78(1)(c); ]

These must:[Art. 84; ]

If the claimed invention lacks reproducibility, this may become relevant under the requirements of sufficiency of disclosure or inventive step. The technical effect achieved by the invention solves the problem which underlies the application. If an invention lacks reproducibility because its desired technical effect as expressed in the claim is not achieved, this results in a lack of sufficient disclosure, which has to be objected to under Art. 83. Otherwise, i.e.