What are the requirements for a valid express abandonment of a patent application?

For a valid express abandonment of a patent application, the following requirements must be met:

• The abandonment must be in writing and signed by a party authorized to sign the application.
• The written abandonment must identify the application number and include a statement of intent to abandon the application.
• The abandonment must be filed in the USPTO during the pendency of the application.

As stated in MPEP 711.01: ‘An express abandonment must be filed in the Patent and Trademark Office during the pendency of the application, and will not be recognized if filed in an application not pending.’