Means plus function language in claims defines the characteristics of a machine or manufacture by including:

Means plus function language is a specific way of claiming an invention under U.S. patent law that focuses on the functions performed by the claimed invention rather than its physical characteristics. When a claim is written in this manner, it must be tied to specific corresponding structures or materials that can perform the stated functions as described in the specification.

The reason option B is the correct choice is that, according to the guidelines established by the USPTO and case law, means plus function claims must be interpreted in light of the structures that are disclosed in the patent specification. This means that the claim is limited to the structures disclosed or equivalent structures that achieve the same function. It ensures that the claim is not overly broad and is anchored in the specific inventions described in the patent application.

In contrast, the other options do not accurately reflect the essence of means plus function claims. For instance, stating that all machines in the marketplace or all specific equipment and devices would be included is too broad, as means plus function claims are specific to the disclosed structures in the patent and not to all possible related devices or machines. Hence, the requirement for corresponding structures or materials in the specification underlines the purpose and validity of means plus function language in claims.