What are the requirements and procedures for filing a petition to revive an abandoned patent application under 37 CFR 1.137(a)?

To revive an abandoned patent application under 37 CFR 1.137(a), the requirements include filing a petition with the USPTO, providing a statement explaining the delay in response, and paying the required fee. The procedures involve submitting the petition within two months of the abandonment date and demonstrating that the delay was unintentional.