Rev. Proc. 2005-66 laid out the basic structure and rules for issuing opinion, advisory, and determination letters and established the five-year remedial amendment cycle for individually designed plans and the six-year remedial amendment cycle for pre-approved plans. The Service and practitioner community are working to improve the operation and efficiency of this program. Rev. Proc. 2007-44, which supersedes Rev. Proc. 2005-66, clarifies and improves the DL program; however, we expect to continue to make appropriate adjustments to the program in the future. Rev. Proc.