Certificate of compliance with GOST R is a document that confirms compliance of products or service to the quality and safety standards. It can be both obligatory or not.
Voluntary certification shall be arranged according to the similar procedure that an obligatory one. However, in case of voluntary certification it is possible to choose the standards compliance with which shall be confirmed.
As far as this document shall officially confirm quality of the product voluntary certification is usually performed in order to attract new customers as well as to demonstrate the high standards of production.