Conformity assessment - a.k.a. 3rd Party Certification or Proof-of-Compliance - is an International Organization for Standardization (ISO) term, also defining the highest order for proof of compliance. Most standards development and product approval activities are currently being modeled after international programs.
The requirements to which compliance is to be proved are usually code requirements, but these, in turn, are typically the requirements of one or more voluntary, consensus standards (see "The Role of Product Standards").
The maximum level of compliance proof or assurance is normally achieved by use of an independent third party whose responsibility includes unannounced plant visitations to select products for compliance testing. Such programs are typically accompanied by the right of the buyer of the service to place the third party's "mark" on the product to demonstrate compliance. The service may also include publication of a list of "certified" products by the third party.
All the model codes and all adopted codes give the enforcement official the power to require some form of proof that a product or system being installed in that particular governmental jurisdiction does, in fact, meet the legal requirements of the installation code.
Conformity assessment provides assurance for regulators and consumers that plastic piping systems meet or exceed performance standards.