In addition to the petition, what specific document related to the corresponding application must be included when applying for PPH?

The correct answer is that when applying for the Patent Prosecution Highway (PPH), a copy of the office action prior to the notice of allowance must be included. This requirement is rooted in the purpose of the PPH program, which is designed to expedite the examination process for patent applications.

When an application is submitted under PPH, the examination results from a patent office where the corresponding application has already been examined are critical. Specifically, the office action prior to the notice of allowance provides insights into the substantive examination conducted by the first patent office and highlights the claims' patentability as determined by that office. This prior examination helps the second patent office assess the patentability of the claims in relation to what has already been reviewed, thereby enhancing the efficiency and speed of the examination process.

In contrast, while a copy of the allowed claims or any limitations may seem relevant, they do not directly contribute to the PPH process in the same essential manner that the office action does. The first communication is also important, but the primary focus is on the assessment that occurs before allowance, which reflects the claims' examination status. Thus, including the office action prior to the notice of allowance is a crucial step in leveraging the benefits of the PPH.