What are the requirements for submitting copies of correspondence in response to a notice about an unlocatable file?

When responding to a notice about an unlocatable file, applicants or patentees must provide copies of correspondence, but there are some exceptions. The MPEP states:

Any appendix or information disclosure statement submitted with an application is not contained in the Office’s database. Therefore, the applicant or patentee must also provide a copy of any appendix or information disclosure statement (except in the limited circumstance discussed below) submitted with the application.

However, there’s an important exception for U.S. patent documents:

Since the Office can obtain copies of U.S. patent documents (U.S. patent application publications and patents) from its internal databases, the Office is not requiring applicants or patentees to provide copies of U.S. patent application publications and patents that are among the applicant’s or patentee’s record of the correspondence between the Office and the applicant or patentee for the application, patent, or other proceeding.

This means that while most documents need to be resubmitted, U.S. patent documents can be omitted from the response.