A Certificate of Correction is requested for which kind of correction?

A Certificate of Correction is specifically designed to address clerical mistakes that do not materially affect the substantive content of the patent. This includes typographical errors, minor misspellings, or other similar errors that might have occurred in the granting process of a patent.

The purpose of the Certificate of Correction is to ensure that the patent accurately reflects the intent of the applicant and corrects any inadvertent errors. It serves to clarify the patent's content without altering its legal scope or the protection afforded by it. This mechanism is an efficient means for the patent owner to correct errors that are clearly unintended and do not alter the substance of the patent claims or rights granted.

Other types of corrections mentioned in the options, such as substantial changes in claims or issues related to inventorship and patent term extensions, require more formal proceedings and cannot be rectified simply through a Certificate of Correction. These actions typically involve additional documentation, potential examination, or other legal processes, demonstrating the specific and limited scope of what a Certificate of Correction can address.