A product category rule (PCR) is defined in ISO 14025 as a set of specific rules, requirements, and guidelines, for developing environmental declarations for one or more products that can fulfill equivalent functions. PCR determine what informations should be gathered and how that information should be evaluated for an environmental declaration.
ASTM International has published the following PCRs.
A Environmental Product Declarations (EPD) provides quantifiable environmental data to compare products that fullfill the same function. In order to create comparable EPDs, they must follow the rules and guidelines called for in the associated PCR.