Phosphonate monoester hydrolase/phosphodiesterase hydrolyses phosphonate monoesters or phosphate diesters using a posttranslationally formed formylglycine as the catalytic nucleophile. PMH is the member of the alkaline phosphatase superfamily. The structure of PMH is more homologous to arylsulfatase than alkaline phosphatase. Sulfatases also use formylglycine as catalytic nucleophile.