Roszdravnadzor published letter about classification rules. If manufacturer have had old registration certificate form without 4n classification code and RZN appointed 4n classification for this medical device – manufcaturer has a right to change this classification code as a part of changing process or separate changing process for medical devices.

You can find official letter in Russian:  014-23752016-from-28-11-2016-russian

and in English: 014-23752016-english-version