What document provides guidance on maintaining a trademark registration?

The document that provides guidance on maintaining a trademark registration is the "keeping your registration alive" webpage. This resource specifically outlines the requirements and procedures necessary for trademark owners to keep their registrations valid. It includes important information on renewal deadlines, necessary documentation, and any maintenance filings that must be submitted to the USPTO to ensure that the trademark remains in force.

The other options do not focus specifically on the maintenance of trademark registrations. The Trademark Act outlines the legal framework for trademarks but does not serve as a maintenance guide. The application serial number guide is related to the application process but does not address maintenance. The cancellation proceedings handbook deals with the process of cancelling trademarks, rather than maintaining them. Hence, the webpage dedicated to keeping registrations alive is the most relevant and practical source for trademark owners seeking guidance on maintaining their trademark rights.