Basic concepts of certification:
"Certification" is defined as "an activity by a third party suspected of being fully trusted to verify that an identified product or service meets a specific standard or normative document ".
The role of third parties falls into two categories:
State or governmental authorities and certification bodies authorized by the State or authority
Certification of Products:
Safety Regulations, EMC、ROHS
International level like IEC
Chapter level like CISPR
Level CE like EN of European standards for harmonization
national level such as GB、GS、UL、FCC etc
Usually when choose power line filters, sometimes there are requirements for product certification.