What is the main subject covered in MPEP 400?

The main subject covered in MPEP 400 is primarily focused on the concept of assignments and ownership of patents. Specifically, it details the procedures and requirements for the assignment of patent applications and patents as well as how ownership rights are transferred and maintained. This section outlines the necessary documents and steps involved in recording assignments with the United States Patent and Trademark Office (USPTO) and clarifies the significance of proper title transfer to ensure legal ownership and rights to patent applications and issued patents.

The reference to Power of Attorney in option C may appear relevant but is actually covered under a different section in the MPEP, emphasizing how to designate an attorney or agent to act on behalf of a patent applicant. In contrast, understanding assignments and ownership is crucial for determining and securing rights to the intellectual property, which is what MPEP 400 fundamentally addresses.

This highlights the significance of accurately maintaining ownership records and the implications they hold for both inventors and assignees, solidifying the importance of this area in patent law.