In addition, in patent practice, at least in the United States, the inventor of a patent application can "become his own lexicographer". In other words, the inventor can give an ordinary word or phrase a special meaning very different from its usual definition. Therefore, the interpretation of the claim must depend on the interpretation of the words in the "specification" of the patent. The "specification" of a patent is a written description of how to make and use the invention.
For example, a claim can be written in the following form:
A method for treating liquid comprises the following steps ...
A rolling screen for screening soil consists of a rolling screen and a bracket. ...
The utility model comprises a pulley and a seat body, and is characterized in that …
A mouse catching device comprises a base member and a spring member placed on a plane. ...
A chemical for cleaning windows contains about10–15% ammonia. ...
In order to exclude others from using a patented invention, the owner (patentee) of the patent needs to prove in court that what others are using belongs to the scope of this patent claim. Therefore, for a claim, the less the number of restrictions that distinguish the invention from the so-called prior art, the more valuable the claim is. On the other hand, when a claim contains fewer restrictions, the greater the chance that it will be covered or read by the prior art, and it will be easily rejected in the examination process or later declared invalid because of its lack of novelty.