Which of the following is a necessary document to apply for PPH?

To successfully apply for the Patent Prosecution Highway (PPH), one critical component of the application process is the petition or request for PPH. This petition serves as an official request that communicates the applicant's intent to benefit from the streamlined examination process that the PPH offers.

The PPH program is designed to expedite the examination of patent applications within participating countries based on a favorable examination result from a corresponding foreign application. The petition outlines the relationship between the applications and demonstrates that the criteria for entering the PPH program have been met, such as a positive ruling on patentability.

The other documents listed may have their own importance, either in the context of general patent application requirements or handling during prosecution, but they are not explicitly required to initiate the PPH process. For instance, while a declaration of inventorship and previous submissions may be necessary for the overall patent filing, they do not specifically pertain to the PPH application as the petition does. Thus, the petition/request for PPH is essential and serves as the foundation for entering this expedited review path.