The terms of a patent assignment must be:

The terms of a patent assignment must be written but do not require recording for the assignment to be valid. A written assignment clarifies the rights being transferred and the specific details regarding the assignor and assignee, which are essential for determining ownership and enforceability of the patent rights.

Recording the assignment, while beneficial for establishing a public record of the ownership and providing constructive notice to third parties, is not a legal requirement for the validity of the assignment itself. Therefore, a patent assignment can be valid solely based on the existence of a written document, even if it is not recorded with the United States Patent and Trademark Office (USPTO).

In the context of the other choices, oral agreements can present significant issues regarding proof and enforceability, which makes them inadequate for patent assignments. Russian law, or any requirement regarding the language in which the assignment must be completed, does not necessitate that it be exclusively in English, which reflects the global nature of patent rights. Notarization is also not a condition for the validity of patent assignments, although it may provide additional proof of authenticity and date of execution if disputes arise. Thus, the key principle is that a written assignment suffices, regardless of the need for recording or any other formalities.