The London Bullion Association's (LBMA) Proactive Monitoring Programme (PAM) reviews the assaying competence of Good Delivery refiners on a three-yearly basis. In addition, it checks that they continue to meet the minimum requirements for refined production and tangible net worth on an annual basis. Three years after the date of original listing, refiners receive a letter from the LBMA instructing them to participate in the programme.
To assist the LBMA with this specific programme, ALS Inspection (An associate member of the LBMA) can be appointed to witness the dip-sampling operation that provides samples for testing by the LBMA's Referees. Generally, a Good Delivery refiner that is listed on both the gold and silver lists will undertake gold and silver PAM at the same time.