The Verification Procedure provides a way to thoroughly evaluate the PM emission reduction capabilities and durability of a variety of diesel emission control strategies as part of a retrofit in-use program. A number of criteria need to be considered when purchasing diesel exhaust retrofits known as "verified diesel emission control strategies" (DECS) or (VDECs) to comply with CARB diesel regulations. For additional information on selecting, installing and maintaining a DECS please visit the Heavy-Duty DECS Installation/Maintenance page.