https://www.uspto.gov/When drafting the patent application, be explicit about the mechanics of your invention. Do not assume anyone will infer the same information you believe is implied in the text. For example, if a mechanical pencil has a high degree of rigidity (e.g., it is made from a hard form of plastic versus a softer type of plastic), which helps with its mechanical operation, the rigidity needs to be expressed in mechanical terms in the patent application. Do not rely on the examiner to infer from a description of the pencil’s operation that the mechanical pencil requires a certain degree of rigidity—make it explicit.
Focusing on the point of novelty can help the patent drafter explicitly describe the various aspects of the invention. The drafter should focus on as many aspects of the point of novelty as possible and build the application around it. For example, if it is the mechanism that automatically progresses lead through a mechanical pencil makes the pencil novel, all aspects of that mechanism should be described in the Detailed Description. First, describe the basic operation of the mechanism. Second, include various parts of the mechanism that might help with, or improve, the functioning of the mechanism. If there are two or more such aspects that improve the function of the mechanism, such as (1) an index finger operated mechanical clicker and (2) a thumb operated mechanical clicker it may be prudent to indicate that the inventive product may be fabricated by incorporating aspect number one only, aspect number two only, or combinations thereof (see Chapter 10, “Written Description Requirement,” for more detail on describing features in a disjunctive manner).
Being explicit in the Detailed Description section is also important if patent protection is sought in foreign countries. Claims are often amended during examination of the patent application to avoid the prior art. In the United States, the USPTO has a more liberal approach in determining what can be inferred from the text of a patent application than foreign patent offices. However, for applications filed in foreign countries, the claim language needs to mimic the language in the specification to a greater degree than patent applications filed in the United States. In other words, the claim limitations that a patent applicant may want to include in a claim after its initial filing must essentially be found word-for-word within the Detailed Description of the patent application when prosecuting foreign patent application. Even though the U.S. takes a more liberal approach, the drafter should strive to make explicit aspects of the invention that the inventor wants to claim in light of possible foreign patent prosecution. This should be done in the event that the patent application is filed in foreign countries that have a strict approach to what information can be included in the amendments made to claims.