Where terms such as "about" or "approximately" are applied to a particular value (e.g. "about 200°C" or "approximately 200°C") or to a range (e.g. "about x to approximately y"), the value or range is interpreted as being as accurate as the method used to measure it. If no error margins are specified in the application, the same principles described in G‑VI, 8.1, apply, i.e. the expression "about 200°C" is interpreted as having the same round-off as "200°C".

When the use of a relative term is allowed in a claim, this term is interpreted by the division in the least restrictive possible way when determining the extension of the subject-matter of the claim. As a consequence, in many cases, a relative term is not limiting the extension of the subject-matter of a claim.

For example, the expression "a thin metal plate" does not limit the feature "metal plate" against the prior art: a metal plate is "thin" only when compared to another one, but it does not define an objective and measurable thickness.

4.6.1 Clarity objections

4.6.2 Interpretation of relative terms

As detailed above, an independent claim must specify explicitly all of the essential features needed to define the invention. This applies except in so far as such features are implied by the generic terms used, e.g. a claim to a "bicycle" does not need to mention the presence of wheels.

In the case of a product claim, if the product is of a well-known kind and the invention lies in modifying it in certain respects, it is sufficient that the claim clearly identifies the product and specifies what is modified and in what way.

Essential features of a claim are those necessary for achieving a technical effect underlying the solution of the technical problem with which the application is concerned (the problem usually being derived from the description). The independent claim(s) must therefore contain all features explicitly described in the description as being necessary to carry out the invention.