Anchor is a special kind of [[Data element (Datum)|datum]] which contains a hash of event ([[Resources/Terms and definitions/Decree|decree]]). It serves as a synchronization event (point) between [[Chain|zerochain and mainchain]]. For example, a "commission value change" [[Resources/Terms and definitions/Decree|decree]] was issued in zerochain, and the anchor for this decree was issued in the mainchain: all transaction [[Data element (Datum)|datums]] in mainchain will be validated using new commission value if they appear after this anchor datum.